The White House has said they are working on evacuation flights and cruise ship departures for American citizens in Israel.

Mike Huckabee, the US Ambassador in Israel, has confirmed that the options are currently voluntary.

It comes as tensions rise between Iran and Israel as the conflict between the two countries escalates.

After Ayatollah Ali Khamenei rejected Donald Trump's demand for unconditional surrender, the President declined to say whether he had made any decision on whether to join Israel's bombing campaign against Iran.

President Trump has ordered the evacuation

People evacuated from Israel disembark from a plane, amid the Israel-Iran conflict in Sofia, Bulgaria

Trump said: "I may do it. I may not do it. I mean, nobody knows what I'm going to do."

Asked for his response to Khamenei rejecting his demand to surrender, President Trump said: "I say, good luck."

Khamenei, 86, rebuked Trump in a recorded speech played on television, his first appearance since Friday.

The Americans "should know that any US military intervention will undoubtedly be accompanied by irreparable damage," he said.

"Intelligent people who know Iran, the Iranian nation and its history will never speak to this nation in threatening language because the Iranian nation will not surrender."

Smoke rises following an Israeli attack in Tehran, Iran,

A Home Front Command Israeli soldier stands next to damaged residential buildings following missile attack from Iran to Israel,

Traffic was backed up on highways leading out of the capital Tehran, a city of 10 million people, as residents sought sanctuary elsewhere.

Arezou, a 31-year-old Tehran resident, told reporters by phone that she had made it out to the nearby resort town of Lavasan.

"We will stay here as long as this war continues. My friend’s house in Tehran was attacked and her brother was injured. They are civilians," she said. "Why are we paying the price for the regime’s decision to pursue a nuclear programme?”

In Israel, sirens rang out warning people of retaliatory Iranian missile strikes. At Ramat Gan city train station east of Tel Aviv, people were lying on city-supplied mattresses lined along the floor or sitting in the odd camping chair, with plastic water bottles strewn about.