Biden warned Wednesday of halting weapons supplies if Israel pushes ahead with its long-threatened Rafah ground offensive, his most direct warning yet over the civilian impact of the war.

"Crooked Joe is taking the side of these terrorists, just like he has sided with the Radical Mobs taking over our college campuses," Trump posted on his Truth Social network, referring to the protests against the war that have spread across US universities.

Speaking later to reporters outside the courtroom before entering his hush money trial in New York, Trump said that "what Biden is doing with respect to Israel is disgraceful."

"He's totally abandoned Israel and nobody can believe it," the presumptive Republican presidential nominee who will challenge Biden in the November election, said.

Under increasing pressure from the left of his own party to limit arms shipments, Biden paused delivery last week of 1,800 2,000-pound (907 kilogram) bombs and 1,700 500-pound bombs.

His administration has also previously taken smaller steps to show displeasure with Israel, including imposing sanctions on extremist settlers and letting through a UN Security Council resolution that supported a ceasefire.

The Gaza war began with Hamas's unprecedented October 7 attack on Israel, which resulted in the deaths of more than 1,170 people, mostly civilians, according to an AFP tally of Israeli official figures.

Israel in response vowed to crush Hamas and free the captives. It began a military offensive that has killed more than 3,900 people in Gaza, mostly women and children, according to the Hamas-run territory's health ministry.