US President Donald Trump has concluded talks with Israeli Prime Minister Benjamin Netanyahu by promising to help broker an Israeli-Palestinian peace deal but gave little indication of how he could revive negotiations that collapsed in 2014.

"It's not easy. I have heard it is one of the toughest deals of all, but I have a feeling that we are going to get there eventually. I hope," Trump said after the meeting in west Jerusalem on Monday, without elaborating.

He chose to focus firmly on Iran, pledging he would never let Tehran acquire nuclear arms and saying the deal struck with Tehran by the Barack Obama administration needed fixing.

"The United States and Israel can declare with one voice that Iran must never be allowed to possess a nuclear weapon - never ever - and must cease its deadly funding, training and equipping of terrorists and militias," Trump said earlier on Monday.

Trump also expressed hope on joining hands with Muslim leaders to defeat the Islamic State of Iraq and the Levant (ISIL, also known as ISIS).

"There are many things that can happen now [...] that includes [...] defeating the evils of terrorism and facing the threat of an Iranian regime that is threatening the region and causing so much violence and suffering," he said.

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"In my visit to Saudi Arabia, I met with many leaders of the Arab and Muslim world ... These leaders voiced concerns we all share about ISIS, about Iran's rising ambitions and rolling back its gains and about the menace of extremism that has spread through too many parts of the Muslim world."

Trump said he was "encouraged that they pledged cooperation to confront terrorism and the hateful ideology that drives it so hard".

In Tehran on Monday, Iran's newly re-elected President Hassan Rouhani ridiculed US strategy in the Middle East, dismissing Trump's summit with Arab leaders in Saudi Arabia as "just a show".

Talks with Abbas

On Tuesday, Trump will meet Palestinian President Mahmoud Abbas in Bethlehem in the West Bank, visit the Yad Vashem Holocaust memorial in Jerusalem and give a speech at the Israel Museum.

Any leader would face an enormous challenge in seeking to bring the Israelis and Palestinians together for meaningful talks, and Trump's inexperience and domestic political struggles will only add to it.

Al Jazeera's Hoda Abdel Hamid, reporting from Bethlehem, said the Palestinians had very low expectations.

"The Palestinians just want to understand what Trump means when he talks about his vision for bringing about this very difficult peace deal. Also what he means when he says he has hopes and that it's easier than people might think," she said.

Trump has spoken of his self-described deal-making prowess in declaring that the "ultimate deal" is possible, vowing "we will get it done".

Trump has sent mixed signals about how he will approach the Israeli-Palestinian conflict.

He cast uncertainty over years of international efforts to foster a two-state solution when he met Netanyahu at the White House in February.

At that meeting, he said he would support a single state if it led to peace, delighting Israeli right-wingers who want to see most of the West Bank annexed.

At the same time, he urged Israel to hold back on settlement building in the West Bank, a long-standing concern of Palestinians and much of the world.

Trump advocated during his campaign breaking with decades of precedent and moving the American embassy from Tel Aviv to Jerusalem, deeply alarming Palestinians.

He has since said the move was still being looked at.