( CNN ) -- Heightening its warnings as anticipated anti-government protests approach , Iran 's government says it will arrest protesters and hold them until April if they disrupt state-sanctioned marches to commemorate the overthrow of the Shah of Iran . Iran is this week celebrating the 31st anniversary of the Islamic Revolution , culminating on February 11 -- a day that marked the end of the country 's Western-backed monarchy and the start of an Islamic republic . A coalition of Iranian reformist groups is urging opponents of the regime to stage non-violent protests on Thursday , on the official anniversary of the Shah 's ouster . The so-called Green Movement has been protesting for social justice , freedom and democracy in demonstrations throughout the country since the disputed June president election . Those arrested for causing `` instability , '' disrupting public order and carrying `` extremist signs '' linked to the Green Movement will be jailed until at least April 9 , the end of the Persian holiday , of Norooz , according to government-run Fars news agency . The holiday marks the start of spring . `` Given the security plans that the police have taken into consideration for tomorrow 's glorious marches ; these ceremonies will be held in complete security and calm , '' Fars quoted an unidentified , informed source as saying Wednesday . `` But if some try to misuse the vast participation and presence of the people ; the police will deal with them firmly and resolutely . '' Anti-government demonstrations began after the disputed June 12 presidential vote , which re-elected hardline President Mahmoud Ahmadinejad over main opposition candidate Mir Hossein Moussavi . Police arrested 4,000 people in the post-election crackdown . At least seven people were killed and hundreds were arrested , witnesses said , as they took to the streets of December 27 during the Shiite Muslim holy period of Ashura . The Iranian government has denied that its security forces killed anyone and has blamed reformists for the violence . On Tuesday , an Iranian court sentenced one person to death and eight others to prison for their parts in anti-government demonstrations in December , the semi-official Fars news agency reported . The nine defendants were tried last week over their roles in protests during Ashura , Fars said , quoting the Tehran judiciary 's public relations office . There are now 10 people sentenced to death and awaiting appeal in connection with the protests . Two men have been executed for participating in anti-government demonstrations , but a lawyer for one of them told CNN her client was already in jail when the protests broke out .
Protesters to be arrested and held until April if they disrupt state-sanctioned marches . Iran is this week celebrating the 31st anniversary of the Islamic Revolution . Marches are to commemorate the overthrow of the Shah of Iran . Reformist groups are urging opponents of the regime to stage non-violent protests .