Donald Trump says Iran must stop funding and training 'terrorists and militias' immediately

US President Donald Trump made the remarks during a press conference in Jerusalem with Israeli President Reuven Rivlin (THOMAS COEX/AFP/Getty Images)

Donald Trump said Iran must immediately cease financial and military support for "terrorists and militias".

The President reiterated that Tehran will never be allowed to possess atomic weapons.

"Most importantly, 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, and it must cease immediately," Mr Trump said at a meeting in Jerusalem with Israeli President Reuven Rivlin.

He went on to say Israel's Arab neighbours are realising they share a "common cause" with Israel in the threat from Iran.

The United States has branded Iran a "state sponsor of terrorism".

It said Tehran's support for Syrian President Bashar al-Assad in Syria's civil war, Houthi rebels in Yemen's civil war and the Hezbollah Shia political party and militia in Lebanon have helped destabilise the Middle East.

In his speech at Mr Rivlin's official residence, Mr Trump said he was deeply encouraged by his conversations with Muslim world leaders in Saudi Arabia.

"Many expressed their resolve to help end terrorism and the spread of radicalisation. Many Muslim nations have already taken steps to begin following through on this commitment," he said.

"There is a growing realisation among your Arab neighbours that they have common cause with you in the threat posed by Iran."

Speaking during his first visit to Israel as president, Mr Trump said there is strong consensus on these issues among the world's nations, including many in the Muslim world.