Tehran, Iran ? Police on Saturday arrested dozens of pro-clergy militants who smashed their way into university dormitories and beat up sleeping students in a wave of violence aimed at putting down protests against Iran’s Islamic government.

The arrests appeared to be an attempt by Iran’s ruling hard-line clerics to rein in their militant supporters, reflecting fears that the violence might only stoke the past week’s anti-government protests, which were the largest in months.

The Islamic regime is worried about alienating a restive public at a time when the United States has stepped up pressure against Tehran over its nuclear program and alleged links to the al-Qaida terror network.

In Washington, the White House called on Iran to “protect the human rights of the students.”

“The United States views with great concern the use of violence against Iranian students peacefully expressing their political views,” spokesman Ari Fleischer said.

The militants, who pledge allegiance to Iran’s supreme leader, Ayatollah Ali Khamenei, usually act with impunity, breaking up demonstrations and punishing protesters.

The past week, they did exactly that against young Iranians who were holding nightly demonstrations since Tuesday, chanting anti-government slogans, including unprecedented calls for Khamenei’s death.

Friday night saw the most intense violence of the week, even though there was no anti-government protest. Militants went on a rampage across the city, beating pedestrians with clubs, brandishing knives, firing machine guns in the air and hurling rocks at homes. Dozens of militants stormed at least two university dormitories, beating up students in their beds and taking several of them away.

“We were sleeping in our beds. Suddenly we heard windows being smashed,” said Mojtaba Najafi, a student who was in the Hemmat dormitory of Allameh Tabatabai University, when the attacks began.

“It was the most brutal way of attacking a human being. They beat up the guard before entering our dormitory. They see no borders, no limits.”

About 200 students were sleeping in their rooms, Najafi said. More than 50 students were injured and taken to the hospital, and about two dozen had disappeared after the attack.