Washington DC - President Donald Trump said Wednesday he was still considering whether to join the Israeli aggression on Iran and continued to threaten Tehran.

Speaking as he watched installation of a new flagpole at the White House, Trump added that his patience "had already run out" with Iran and repeated his call for the Islamic republic's "unconditional surrender," which was categorically rejected by Ayatollah Ali Khamenei.

"I may do it, I may not do it. I mean, nobody knows what I'm going to do," Trump told reporters on the South Lawn when asked if he had decided whether to launch US air strikes.

"I can tell you this, that Iran's got a lot of trouble, and they want to negotiate."

Donald Trump Trump convenes National Security Council as US considers joining Israel's campaign against Iran

Trump claimed Iran had suggested sending officials to the White House to negotiate on Tehran's nuclear program to end Israel's air assault.

"I said it's very late to be talking. We may meet. There's a big difference between now and a week ago, right? Big difference," he added.

"They've suggested that they come to the White House. That's, you know, courageous, but it's, like, not easy for them to do."

Asked about Tuesday's social media post in which he demanded Iran's "UNCONDITIONAL SURRENDER," Trump said it meant "we go and blow up all the nuclear stuff that's all over the place."

The Republican compared Iran to "schoolyard bullies", adding: "And now they're not bullies anymore, but we'll see what happens."

When asked if it was too late for talks to recommence, however, he said: "Nothing is too late."

Israel's unprovoked attack on Iran came despite repeated reports by US intelligence agencies that Tehran was not actively pursuing nuclear weapons.

It was launched with full knowledge of the Trump administration and in the middle of diplomatic negotiations to establish a new agreement on Iran's nuclear program, seven years after Trump himself unilateral ripped up the old deal.