Hundreds of helmeted police swarmed the site of a pro-Palestinian protest at the University of California at Los Angeles early on Thursday, arresting demonstrators and dismantling their encampment.

The pre-dawn police crackdown at UCLA marked the latest flashpoint in mounting tensions on US college campuses, where protests over Israel's war in Gaza have led to student clashes with each other and with law enforcement.

Prior to moving in, police urged demonstrators in repeated loudspeaker announcements to clear the protest zone, which occupied a central plaza about the size of a football field.

After massing around the campus for hours, officers eventually moved through the area in lines holding batons as protesters - some in white helmets - linked arms, attempting to block their advance.

Live TV footage showed officers taking down tents and removing the encampment, while arrested protesters sat with their hands restrained behind their backs with zip-ties.

Students have rallied or set up tent encampments at dozens of universities in recent days, calling for an immediate ceasefire in Gaza and demanding schools divest from companies that support Israel's government.

Many colleges, including Columbia University in New York City, have called in police to quell the protests. (Reuters)