Netanyahu praises Trump's 'courageous decision' on Iran while Saudi Arabia backs US leader's 'firm strategy'

Israel and Saudi Arabia both showed their support to US President Donald Trump on Friday after he refused to certify the 2015 Iranian nuclear deal.

Israel's Prime Minister Binyamin Netanyahu congratulated Trump on his "courageous decision" while Saudi Arabia said it backed the US leader's "firm strategy."

"I congratulate President Trump for his courageous decision today. He boldly confronted Iran's terrorist regime," Netanyahu said in a video in English.

"If the Iran deal is left unchanged, on thing is absolutely certain. In a few years time, the world's foremost terrorist regime will have an arsenal of nuclear weapons and that's a tremendous danger for our collective future," he said.

Netanyahu has repeatedly denounced the deal signed by Iran and six world powers including the United States, which saw sanctions on Iran lifted in exchange for curbs to its nuclear programme.

Meanwhile, Saudi Arabia said it backed Trump's "firm strategy" on regional rival Iran.

"The kingdom backs and welcomes the firm strategy on Iran and its aggressive policy that was announced by US President Donald Trump," the official Saudi Press Agency said in a statement.

The Sunni monarchy in Saudi Arabia has for years accused Shia Iran of "destabilising" the Arab world. The region's two powerhouses also support opposite sides in the wars in Syria and Yemen.

The two countries severed diplomatic ties in January 2016 after Iranians stormed Saudi Arabia's embassy and consulate in response to the execution of a prominent Shia cleric.

Saudi Arabia and its fellow Sunni Arab states had strong reservations over the deal brokered between Iran and six world powers, including the United States, in 2015 but reluctantly accepted it.

In Friday's statement, Riyadh said it would continue working with the United States and other world powers to "deal with the dangers represented by Iran's policy on all levels".

On Friday, Trump stopped short of withdrawing from the accord, but "decertified" his support for the agreement and left its fate in the hands of Congress.

"President Trump has just created an opportunity to fix this bad deal, to roll back Iran's aggression and to confront its criminal support of terrorism," the Israeli premier said.

Iranian President Hassan Rouhani hit back following Trump's speech saying: "Today the United States is more than ever isolated in its opposition to the nuclear deal and in its plots against the Iranian people.

"What was heard today was nothing but the repetition of baseless accusations and swear words that they have repeated for years," Rouhani added.

"The Iranian nation does not expect anything else from you."

Rouhani dismissed Trump's threat to tear up the landmark deal between Tehran and the six world powers including Washington if Congress does not impose tough new sanctions on Iran.

"He has not studied international law. Can a president annul a multilateral international treaty on his own?" Rouhani said.

"Apparently he doesn't know that this agreement is not a bilateral agreement solely between Iran and the United States."

Agencies contributed to this report