President Trump on Monday said he isn't concerned about escalating tensions between the U.S. and Iran, hours after he threatened severe consequences against the regime over its "demented" comments about America.

"Not at all," Trump responded when asked by reporters at a White House event if he was worried about provoking Iran.

The president lashed out at Iranian leader Hassan Rouhani in a pre-dawn tweet Monday morning, promising "consequences the likes of which few throughout history have ever suffered before" if officials in Tehran continue their virulent attacks against the United States.

"Be cautious!" Trump warned at the end of the tweet.

The president's stern warning comes just days after Secretary of State Mike Pompeo described the steps the Trump administration is currently taking to reimpose sanctions against Iran as part of the president's withdrawal from a nuclear agreement with the country.

Pompeo also blasted the regime for having "heartlessly repressed its own people's human rights, dignity and fundamental freedoms" during a speech Sunday at the Ronald Reagan presidential library in California.

"The United States under President Trump will not stay silent either," he said.

Top Iranian officials dismissed Trump's threat in tweets of their own on Monday, including Foreign Minister Mohammad Javad Zarif who mocked the president using his own words.

"COLOR US UNIMPRESSED: The world heard even harsher bluster a few months ago. And Iranians have heard them – albeit more civilized ones for 40 yrs. We've been around for millennia & seen fall of empires, incl our own, which lasted more than the life of some countries. BE CAUTIOUS!" Zarif tweeted.