Iran must never be allowed to have nuke

US President Donald Trump travelled to Jerusalem yesterday to seek ways to achieve Israeli-Palestinian peace, but also used the visit to again lash out at Iran.

Trump's visit is part of his first trip abroad as president and follows an initial stop in Saudi Arabia, where he urged Islamic leaders to confront extremism while also criticising Iran.

Trump landed in Tel Aviv yesterday afternoon, welcomed by officials including Israeli Prime Minister Benjamin Netanyahu as he walked along a red carpet ahead of a brief ceremony.

He later travelled by helicopter to Jerusalem and, in remarks at Israeli President Reuven Rivlin's residence, launched his latest salvo against Iran.

"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.

"And it must cease immediately."

While in Saudi Arabia, Trump accused Iran of fuelling "the fires of sectarian conflict and terror" while calling for its international isolation.

Security was extremely tight for the Israeli leg of the visit, with police deploying some 10,000 officers.

The alleys and passageways of Jerusalem's ancient Old City, which Trump visited later in the day, were essentially under lockdown.

Ahead of talks with Netanyahu, Trump was touring two iconic sites in Jerusalem, a city holy to Muslims, Christians and Jews.