( CNN ) -- Just steps away from the courthouse where a jury decided George Zimmerman 's fate , demonstrators vowed that their fight was n't over . `` Nationwide protest to demand justice , '' they chanted after the jury 's not guilty verdict in Sanford , Florida , cleared Zimmerman in the shooting death of Trayvon Martin . It was n't long before some appeared to be heeding their call . Protesters rallied in Los Angeles , San Francisco , Chicago , Denver , Baltimore , Detroit , New York and other cities . `` I came here today to stand in solidarity with Trayvon Martin 's family , and everyone else searching for justice for him , and wanting to bring Zimmerman to justice , '' said Kellie Knight . She spoke at a protest at Union Square in New York City . Catch up on the Zimmerman saga in one story . `` If it can happen to her son , it can happen to anybody 's son or daughter , '' she said . Later , a crowd converged on Times Square , chanting : `` This is what democracy looks like . '' The verdict in the closely watched trial echoed far beyond the central Florida city 's borders in a case that drew national attention and has been racially charged from the start . `` Only white life is protected in America , '' one protester in Washington shouted early Sunday . A crowd lined up outside the White House and sang `` Amazing Grace . '' Others chanted `` No justice , no peace '' and `` Trayvon was murdered '' as they marched , freelance photographer Michael Kandel told CNN 's iReport . The atmosphere was tense as demonstrators demanded that the government investigate further , Kandel said . `` They believe that this is a civil rights issue that must become the topic of a national conversation in the coming days , '' he said . `` They did not believe justice had been served and were pleading for it . '' In Dallas , protesters waved signs that said , `` Justice system is a joke , '' CNN affiliate WFAA reported . Some demonstrators in Denver , Baltimore and Detroit wore hooded sweatshirts like the one Martin wore when he was killed . In Chicago 's Daley Plaza , protesters vowed to use technology to push for change . `` It 's the 21st century . We 've got Twitter . We 've got Instagram . We 've got Facebook , we 've got all these things that our elders did not have , '' one woman told the crowd . `` We have resources . '' Verdict does n't end debate in Martin 's death . Pushing for peace . President Barack Obama called Sunday for `` calm reflection , '' acknowledging the Zimmerman case has stirs strong emotions . `` And in the wake of the verdict , I know those passions may be running even higher , '' he said . `` I now ask every American to respect the call for calm reflection from two parents who lost their young son . And as we do , we should ask ourselves if we 're doing all we can to widen the circle of compassion and understanding in our own communities . `` We should ask ourselves if we 're doing all we can to stem the tide of gun violence that claims too many lives across this country on a daily basis , '' Obama said . Most protests have been peaceful , though there were some reports of property damage at a protest in Oakland , California . `` I think we should , frankly , right now be celebrating the fact that we 've seen a generation of young people respond by using our system , raising their voices , but not using their fists , '' NAACP President Benjamin Jealous told CNN 's `` State of the Union '' on Sunday . Analysis : The race factor in Zimmerman 's trial . The Rev . Jesse Jackson called for protests to continue , and to remain peaceful . `` There will be protests , but they must be carried out with dignity and discipline , '' he told CNN 's `` New Day . '' `` Let no act discredit the legacy of Trayvon Martin . In the long run , we will prevail in the struggle for justice . Any act of violence could serve to undermine the innocent blood and moral authority of Trayvon . What will happen if there , in fact , are riots , it gives sympathy to Zimmerman , and discredits Trayvon . Trayvon deserves sympathy . Zimmerman and his school of thought does not . '' Zimmerman , his family and their supporters have denied allegations of racism and argued that civil rights groups are being incendiary without facts to back up their claims . `` We have a verdict . I think we should really take a step back , respect that verdict , respect those six women -- an all-women jury , who had to make a really tough call and had to look at this outside all the emotions that were stirred up , and all of the racial innuendo that was stirred up , and just kind of look at the facts , '' Zimmerman 's brother , Robert Zimmerman Jr. , told CNN on Sunday morning . `` And the facts spoke for themselves . '' Some applauded the jury for siding with the neighborhood watch volunteer 's claims that he shot the teen in self-defense . Others said prosecutors failed to prove their case beyond a reasonable doubt . Some said the trial was a referendum on race that confirmed what they knew all along . `` That 's our society , '' Terri Weems said as she headed into church in Washington on Sunday morning . `` We expected not to be given justice . We have n't been dealt justice all this time . ... It 's very disheartening . '' Zimmerman could still be held responsible for Martin 's death . Reactions from the pulpit . In churches around the country , the trial was a hot topic on Sunday . Donna Holmes-Lockett , who was also heading into church in Washington , said she was surprised by the verdict . Zimmerman should have been punished for the shooting , she said . `` As a mother of black males , I have three sons , it makes me nervous about the reaction of the public toward the situations . I felt like he should have got some kind of , something . He 's just walking away free . He did shoot him . It 's like it 's OK , '' she said . `` I think if it was a black crime on a black person , it would have been a different outcome . '' At Ebenezer Baptist Church in Atlanta , the pastor called for all parishioners under 18 years old to step forward in a tribute to Martin . `` The world needs your voice . Do n't let anybody tell you that you 're a nobody . We love you and we 're counting on you , '' he told them . Why this verdict ? `` Nobody gets nervous seeing you talk bad and look bad . If you really want to strike fear in the hearts of your adversaries , if you really want to be a real threat , make sure God is in your heart ( and ) knowledge is in your head . '' At churches with close ties to the case , Sunday was a time to reflect and pray . `` We 're leaning in and depending on you this morning , oh God , for all of our help , '' a man said from the pulpit at the Allen Chapel AME Church in Sanford , where a town hall meeting was held after the shooting . `` We 're not depending on the Sanford Police Department . We 're not depending on Seminole County Sheriff . We 're not depending on the courts of Seminole County , Florida . '' Several members of Martin 's family attended services at Antioch Missionary Baptist Church in Opa-locka , Florida . `` We 're very concerned , very hurt and very disappointed at this point , but we know in the end God will prevail and justice will be served , '' said Roberta Felton , a cousin . While the Martin family grieves , Pastor Arthur Jackson III said , the community must prepare to take action . `` I believe this situation has not paralyzed us , has not traumatized us , but is mobilizing us , '' he said . `` It has been a call to rally at the polls , to vote ... to change these unjust laws . '' Trayvon 's dad : My heart is broken , my faith is not . CNN 's Victor Blackwell , Nick Valencia , Jonathan Helman , Jareen Imam , John Zarrella , Jennifer Hauser , Emanuella Grinberg and Alicia Stewart contributed to this report .
NEW : Protesters rally in Detroit , New York , New York and Denver . NEW : `` If it can happen to her son , it can happen to anybody 's son or daughter , '' says one . Obama urges `` calm reflection , '' asks American to reflect on toll of gun violence . Leaders call for protests to remain peaceful , push for change .