Turkey's president blasted American authorities for their "cruelty" in cracking down on pro-Palestinian protests at schools across the country, saying the demonsrators are "protesting the massacre" in Gaza, according to a report.

Protests against Israel's war against Hamas in Gaza have spread across the United States, prompting the police to clamp down on protests at Columbia University in New York City and at UCLA.

"Conscientious students and academics including anti-Zionist Jews at some prestigious American universities are protesting the massacre (in Gaza)," Recep Tayyip Erdogan said in Turkey's capital Ankara, Reuters reported.

"These people are being subjected to violence, cruelty, suffering, and even torture for saying the massacre has to stop," he said, noting that university staff were being "sacked and lynched" for supporting the protesters.

"The limits of Western democracy are drawn by Israel's interests," the leader of Turkey, a NATO ally to the U.S., said. "Whatever infringes on Israel's interests is anti-democratic, antisemitic for them."

In the past couple of days, police dismantled encampments at UCLA, Columbia and other schools as Jewish students say they fear for their safety on campus amid the protests.

President Joe Biden, addressing the turmoil in a White House speech Thursday, denounced hate speech but backed the right to protest.

"We are not an authoritarian nation where we silence people or squash dissent," Biden said.

"The American people are heard. In fact, peaceful protest is in the best tradition of how Americans respond to consequential issues. But, but neither are we a lawless country."