The US Virtual Embassy Iran on Monday updated a travel warning urging U.S. citizens to leave Iran immediately amid the unrest across the Middle East country.

"U.S. citizens should expect continued internet outages, plan alternative means of communication, and, if safe to do so, consider departing Iran by land to Armenia or Türkiye," said the virtual embassy in a statement on its website, adding that U.S.-Iranian dual nationals must exit Iran on Iranian passports since the Iranian government does not recognize dual nationality.

"U.S. nationals are at significant risk of questioning, arrest, and detention in Iran," it said.

According to the statement, airlines continue to limit or cancel flights to and from Iran, with several suspending services until Friday.

The U.S. Department of State has long designated Iran as a level 4 "Do Not Travel" destination, warning that U.S. citizens should not travel there for any reason and that those in Iran should leave immediately due to serious security risks.

Earlier on Monday, White House press secretary Karoline Leavitt said diplomacy remained the preferred approach in U.S. dealing with Iran, though the Trump administration will not rule out military options if necessary.

"What President Donald Trump will do next only he knows. So the world will have to keep waiting and guessing, and we will let him decide," she said on Fox News.

Trump said Sunday that his administration is weighing "some very strong options," including potential military action against Iran, and that Iran was "starting" to cross the U.S. red line.

There is no U.S. Embassy or consular presence in Iran, and the Swiss Embassy in Tehran acts as the protecting power for U.S. interests, but the services are limited.

Protests have erupted in Iran's several cities since late December over the sharp fall in the national currency rial and long-standing economic hardships. The reported death toll from the unrest on both sides of the security forces and civilians is mounting.