The crowd around her chanted for democracy in Iran yesterday, and Zolal Habibi thought of her father. She said Mohammad Hossein Habibi, a writer and human rights activist, was killed in 1988 in Iran for speaking out against the Iranian government.

Habibi, 23, joined thousands of Iranian Americans yesterday at a rally outside the U.S. Capitol to denounce human rights abuses, political executions and nuclear ambitions of an Islamic republic that they called an oppressive regime. Habibi wiped tears from her eyes as a large television screen showed pictures of the victims of political and religious executions.

"I know that my dad would be proud of me today," she said.

Iranian American families came to Washington from across the country for the march down Pennsylvania Avenue NW and rally outside the Capitol. Organizers said 15,000 participated. U.S. Capitol Police Chief Terrance W. Gainer said last night that the rally drew a significant crowd but that he did not believe turnout reached 15,000.

Two Virginia-based groups, the Council for Freedom and Democracy in Iran and the Global Coalition Against Fundamentalism, sponsored the event. One of the goals of the demonstration was to call on U.S. leaders to refer Iran's nuclear file to the U.N. Security Council for economic sanctions. Men and women of all ages waved the green, white and red flag of Iran and held up banners reading "A-bomb for Iran, nightmare for the world" and "Stop Iran's nukes."

"As soon as they put their hands on nuclear power, they're going to hold the entire world hostage," said Los Angeles resident Hassan Haddadi, 47, who flew to Washington for the rally and marched with his wife, sister and two children. "And they're not too far from having that power."

Secretary of State Colin L. Powell said Wednesday that the United States has information that Iran is working to adapt missiles to deliver a nuclear weapon. Although the information was reportedly from a single, unverified source, it spurred those at the rally. The gathering precedes a meeting next week of the International Atomic Energy Agency.

A second demand was that an Iranian rebel group be taken off the U.S. list of terrorist organizations. The group, Mujaheddin-e Khalq, also known as the People's Mujaheddin of Iran, advocates a secular government to replace the theocratic regime in Iran.

Critics accuse the group of terrorism, including the murder of U.S. citizens. The group has fighters in neighboring Iraq who formerly received support from the government of Saddam Hussein. Some Pentagon officials have argued that the group has been engaged in legitimate armed resistance against a dictatorial, anti-American government.

Kurtis Cooper, a State Department spokesman, said the People's Mujaheddin is on the terrorist list "because the secretary decided that it met the criteria of being a foreign terrorist organization." The department has said in the past that the group killed several U.S. military personnel and defense contractors in the 1970s, allegations denied by the group's supporters.

Organizers said yesterday that the Clinton administration put the group on the list in 1997 to appease the Iranian government. U.S. Rep. Bob Filner (D-Calif.) was one of several rally speakers who declared their support for the group, saying the People's Mujaheddin is a legitimate democratic opposition group that is the victim of an "international blacklisting."

Children ran through the crowd with signs hung around their necks declaring, "My father is not a terrorist." Two large pictures of the husband-and-wife leadership of the People's Mujaheddin, Massoud and Maryam Rajavi, were displayed on a stage at Upper Senate Park, and a taped message from Maryam Rajavi was broadcast.

Hajar Mojahedzadeh, 18, said her parents were killed by the Iranian government. "The regime has taken both of my parents from me," she said. She said yesterday's demonstration -- in which thousands rallied outside a center of power protected by constitutional rights to free expression -- was "what we want to be able to bring to Iran."

Iranians protest Iran's nuclear ambitions, among other things, at Upper Senate Park. Organizers said the crowd numbered 15,000, a figure U.S. Capitol Police Chief Terrance W. Gainer said he doubted.Akram, left, and Zahra Rahimi of Holland react to video footage of human rights violations by Iran.