"We will keep radical Islamic terrorists the hell out of our country," Trump told the audience attending the annual summit of the Republican Jewish Coalition.

"You remember the travel ban? On day one I will restore our travel ban."

At the start of his presidency in 2017, Trump imposed sweeping restrictions on the entry of travelers from Iran, Libya, Somalia, Syria, Yemen, and, initially, Iraq and Sudan.

The order was quickly challenged in court as discriminatory against a religious group, but the bans, along with Trump's hard-line anti-immigration agenda, were popular with his base.

President Joe Biden reversed the ban in his first week in office in 2021.

Biden "was proud to overturn the vile, un-American Muslim ban enacted by his predecessor," a White House spokesman said.

The former US leader was among several Republican hopefuls lining up at the gathering of influential Jewish donors to pledge unwavering support for Israel in its war on Gaza.

Trump told the event, held in Las Vegas, in the southwestern state of Nevada, that he would "defend our friend and ally in the State of Israel like nobody has ever."

The former reality show host, the overwhelming favorite to win the party nomination to run against Biden next year despite facing multiple criminal prosecutions, spoke after sparking fury in recent weeks by describing Lebanon-based Islamist group Hezbollah as "very smart" and criticizing Israeli Prime Minister Benjamin Netanyahu.