"We call for a halt to the crackdown on voices advocating for peace and freedom," Sadr said in a statement.

"The voice of American universities demanding an end to Zionist terrorism is our voice."

Sadr once led a militia fighting American forces following the 2003 US-led invasion that toppled dictator Saddam Hussein.

He retains a devoted following of millions among the country's majority Shiite Muslim population, and wields great influence over Iraqi politics.

Protests and encampments have taken place at campuses across the United States, Israel's largest military supplier.

Student protesters say they are expressing solidarity with Palestinians in Gaza, where the death toll since October 7 is at least 34,388, according to the health ministry in the Hamas-run Palestinian territory.

In response to the growing protests, police have carried out large-scale arrests across the country, at times using chemical irritants and Tasers to disperse activists.

The war in Gaza began when Hamas militants from the territory attacked Israel on October 7, resulting in the death of around 1,170 people in Israel, mostly civilians, according to an AFP tally of Israeli official figures.

Militants also seized hostages, 129 of whom Israel estimates remain in Gaza, including 34 who the military says are dead.

Israel vowed to destroy Hamas and has carried out relentless bombardment of Gaza alongside a ground invasion.

All Iraqi political factions support the Palestinian cause, and like its neighbour Iran, Israel's sworn enemy, Iraq does not recognise the Israeli state.