President Donald Trump on Friday said "bad, bad things will happen to Iran" if the Middle Eastern country continues down the path to developing nuclear weapons.

Trump addressed Iran while taking questions from reporters in the Oval Office after swearing in Alina Habba as U.S. Attorney for the District of New Jersey.

"Iran is very high on my list of things to watch," Trump said. "As you probably know, I sent them a letter just recently and I said, 'You're going to have to make a decision one way or the other.' And we're going to either have to talk and talk it out or very bad things are going to happen to Iran, and I don’t want that to happen.

"My big preference is we work it out with Iran. But if we don’t work it out, bad, bad things are going to happen to Iran."

Trump's answer came being asked about Iranian-made drones being used by Russia to attack Ukraine.