US President Donald Trump issued a stark warning to Israel over annexing the West Bank in an interview published on Thursday, as visiting Secretary of State Marco Rubio voiced confidence that a US-backed ceasefire in Gaza would hold.

Trump's remarks were made to Time magazine by telephone on October 15 – just days after the Gaza truce plan he spearheaded took effect – but were only published on Thursday.

"It won't happen," Trump said when asked about calls in Israel to annex the Palestinian West Bank, which has been occupied by Israel since 1967. "It won't happen because I gave my word to the Arab countries."

He added: "Israel would lose all of its support from the United States if that happened."

Israeli lawmakers on Wednesday advanced two bills paving the way for West Bank annexation, leading to condemnation on Thursday from US Vice President JD Vance, who was in Israel at the time and who echoed Trump's comments.

When asked on Thursday if he was concerned by the votes, Trump told reporters at the White House: "Don't worry about the West Bank. Israel's not going to do anything with the West Bank."

The United States remains Israel's most important military and diplomatic supporter.

Israeli Prime Minister Benjamin Netanyahu's Likud party boycotted and criticised the vote, though members of his ruling coalition support annexation.

Arab and Muslim countries, which the US has been courting to provide troops and money for a stabilisation force in Gaza – a key element of Trump's ceasefire plan -- have warned that annexation of the West Bank is a red line.

In a joint statement carried by Saudi state media on Thursday, more than a dozen such states including Saudi Arabia, Jordan and Turkey condemned the Israeli parliament's vote.

Rubio, one of a string of top US officials to visit Israel in recent days, had warned before his arrival that the annexation moves were "threatening" to the fragile ceasefire in Gaza.

But he expressed confidence in the truce after meeting with Netanyahu on Thursday.

"We feel confident and positive about the progress that's being made. We're clear-eyed about the challenges, too," said Rubio, just hours after Vance wrapped up his own three-day visit.

As he ended his trip, Vance hit out at the votes in Israel's parliament in favour of examining two annexation bills, which mean they will be brought forward for further readings.

"If it was a political stunt it was a very stupid political stunt and I personally take some insult to it," Vance said.

"The West Bank is not going to be annexed by Israel, the policy of the Trump administration is that the West Bank will not be annexed by Israel, that will continue to be our policy."

Netanyahu, standing next to Rubio after their meeting Thursday, was quick to avoid any suggestion of tension with Washington, calling the secretary an "extraordinary friend of Israel" and saying that the back-to-back visits were part of a "circle of trust and partnership". (AFP)