Iran's Islam-based leadership staged a massive rally yesterday that drew more than 100,000 faithful into Tehran's streets to affirm support for clerical rule and counter a week of protests by students eager for a more tolerant society.

The demonstration was arranged by officials supporting the country's supreme religious leader, Ayatollah Ali Khamenei, and endorsed by organizations favorable to its democratically elected and reform-minded president, Mohammed Khatemi. It signaled a desire for calm that now seems shared by the religious establishment--the protesters' main target--as well as by government reformers, including Khatemi, whose campaign was cheered repeatedly during the demonstrations.

The students who mounted sometimes violent confrontations with police and Islamic militias over six straight days stayed off the streets and announced a suspension of their protests. Their decision was in apparent response to a warning Tuesday from Khatemi and others--including the main pro-reform newspapers--that the protest movement was degenerating into riots and must be stopped before things escalated out of control.

"We will resolutely and decisively quell any attempt to rebel," Hassan Rowhani, secretary of the Supreme Council for National Security, Iran's top security body, told the crowd yesterday, according to news service reports from Tehran.

Khamenei, in a statement published yesterday, blamed the unrest on "the mean and wretched enemies of Islam and the revolution"--and the United States in particular.

U.S. officials, while following events with keen interest, kept a low profile for fear that anything they say in support of the students will be used by hard-liners as further support for Khamenei's claim.

"We believe that the events in Iran are significant," State Department spokesman James P. Rubin said at his regular briefing yesterday. "We're obviously following them closely."

But he added, "Without an embassy, we are not in a position to follow developments on the ground as closely as we would like, and it is difficult to make authoritative assessments about events that are rapidly unfolding, so we're not going to speculate about it."

The pro-government demonstrators in Tehran chanted "Death to America"--a familiar refrain since the late Ayatollah Ruhollah Khomeini led the 1979 revolution that toppled the pro-American monarchy.

But according to the reports from Tehran, speakers also made statements of support for the originally peaceful student protests of a week ago. They repeated pledges to investigate abuses by the security forces, such as the police raid on a Tehran University dormitory last Thursday that touched off the week of protests.

Students have played an "outstanding role" in Iranian society, Rowhani told the crowd. He added that security agencies will continue investigating the "tragic dormitory incident . . . until all the roots which caused the incident are investigated and reported to the public."

Foreign analysts said official statements expressing sympathy with the original student protests and promising an investigation of the police raid indicated that the government is shaken by the unrest, which could eventually strengthen Khatemi's reformist movement.

"Instead of being an anti-demonstration, it is pro the students and pro the regime, running the two things together" in a "very sophisticated" compromise meant to forestall further unrest, said Patrick Clawson, research director at the Washington Institute for Near East Policy.

Khatemi, elected in a landslide in 1997, supports both Iran's underlying commitment to Islam and building a more secular and open society, moving in incremental steps that frequently have brought him into conflict with religious leaders under Khamenei's banner.

Originally modest in size and held to protest the closing of a liberal newspaper, the gatherings at Tehran University exploded after the dormitory raid, growing to include as many as 25,000 students.

By Tuesday, with students ignoring official appeals for calm, the demonstrations triggered a crackdown by baton-wielding security forces backed by Islamic militia squads linked to conservative Islamic leaders in the government. Security forces arrested an unknown number of demonstrators. A student group claiming to speak for the demonstrators said that, while protests are suspended for now, the students still want more information on those killed in the protests--the official count is two--and punishment for two police officers who were fired for ordering the dormitory raid.

CAPTION: A demonstrator stands beneath a portrait of Iran's supreme leader, Ayatollah Khamenei.

CAPTION: A Counter-Demonstration in Tehran: Supporters of Iran's Islamic government carry banners during a rally that drew more than 100,000 into Tehran's streets. The rally was meant to counter a week of protests by students eager for a more tolerant society. Though arranged by officials supporting the country's supreme religious leader, it was endorsed by groups favorable to its reform-minded president.