Donald Trump has issued Iran with an ultimatum as the US President confirmed a deadline for a decision on joining Israel's Tehran bombing blitz.

Issuing a statement through the White House's Press Secretary Karoline Leavitt, Trump said a decision will be made "within two weeks".

Leavitt said the President believes there is "a substantial chance of negotiation" with Iran.

While she insisted Trump was pursuing a diplomatic solution with Iran, his top priority was ensuring that Tehran could not obtain a nuclear weapon.

Donald Trump has issued an update

Citing a direct quotation from Trump, Leavitt told reporters: "Based on the fact that there's a substantial chance of negotiations that may or may not take place with Iran in the near future, I will make my decision whether or not to go within the next two weeks."

She continued: "The president is always interested in a diplomatic solution...he is a peacemaker in chief. He is the peace through strength president. And so if there's a chance for diplomacy, the president's always going to grab it...but he's not afraid to use strength as well I will add."

Israel bombed nuclear targets in Iran on Thursday and Iran fired missiles and drones at Israel after hitting an Israeli hospital overnight, as the conflict ramped up between the two countries.

Leavitt said Trump had been briefed on the Israeli operation and Iran would face grave consequences if it did not agree to halt its work on a nuclear weapon.

White House Press Secretary Karoline Leavitt holds a press briefing