The official, Abdolhamid Ahmad, the deputy sports minister, called for a new atmosphere in stadiums, which many Iranians consider too rowdy and “not Islamic enough” for women. “Stadiums must become family-oriented, and the atmosphere there must be softened,” Mr. Ahmad said. He added that there were some sports that women were not interested in, “nor is their attendance possible, because these sports are for men.” He did not say which sports he meant.

The decision, if put in effect, will be a big victory for President Hassan Rouhani, who has been trying to allow Iranians more personal freedoms and to adjust laws that are seen as outdated as Iran becomes an increasingly urbanized society. Iran’s National Security Council, which is supervised by the Interior Ministry, confirmed the change two weeks ago, but the official announcement was delayed until Saturday, two days after Iran reached an agreement with the United States and five other world powers on the parameters for an accord on Iran’s nuclear program.

Although challenges to entrenched policies and conservative sensibilities often encounter resistance from hard-liners, the news cheered activists working for change. “I am very happy,” said Najiyeh Allahdad, a 38-year old activist who has campaigned for women to be allowed into stadiums. “We have done all we could to get our rights back. This should have happened some time ago. It is now clear for me that this government is really trying hard to improve our lives.”

Shiite Islam, the state religion in Iran, generally tries to separate men and women. But compared with countries like Saudi Arabia, where the segregation of the sexes is widely enforced, Iran takes a more pragmatic approach. For instance, buses and trains have special compartments for women, but shared taxis do not.

During official and religious gatherings, men and women are allowed to mix, but at most universities, they are not. Many of these measures are not codified in laws but are results of decisions made by bodies like the National Security Council in consultation with religious leaders.