Former White House Communications Director Anthony Scaramucci believes it would be "very smart" for Iran to de-escalate tensions with the U.S., amid fears of another military confrontation in the Middle East.
President Donald Trump announced fresh sanctions on the Islamic Republic on Monday, following the downing of an unmanned American drone last week.
The U.S. president also warned an Iranian attack on Americans would be met with "great and overwhelming force" and "obliteration."
Iran responded to the additional sanctions by calling them "outrageous and idiotic" and suggested the White House was suffering from a "mental illness."
"The only thing I would say to people in Iran is I would be very careful with President Trump because he is not the kind of guy that is a politician," Scaramucci told CNBC's Hadley Gamble in Manama, Bahrain on Wednesday.
"He has lived his entire life without fear and so I would just be cautious with him. He just invested $1.4 trillion in the last two years in the United States military and so he means what he says," he added.
The Stockholm International Peace Research Institute (SIPRI) estimated that America's military spending amounted to $1.255 trillion over 2017 and 2018. The U.S. is by far the world's biggest spender when it comes to defense, accounting for 36% of total global military expenditure in 2018.
Scaramucci was fired from his role as White House communications director after just 10 days in the role in 2017, following controversial comments about his colleagues.
Last week, U.S. officials said an Iranian surface-to-air missile shot down an American military surveillance drone over the Strait of Hormuz — the world's busiest transit lane for seaborne oil shipments. Iran said the aircraft violated its airspace. Hours later, Trump said Iran made a "very big mistake" by shooting down the spy drone.
On Thursday, he approved military strikes on Iran before calling them off, saying the attack would have been disproportionate to Iran's downing of an unmanned American surveillance drone.
"It would be very smart on their part to de-escalate. The other thing he (Trump) said, which I know he means, is that he wants peace with the Iranians," Scaramucci said.
"You have to love his leadership, he is a very fearless guy," he added.
Tensions between the U.S. and Iran have spiked since May 2018, when Trump withdrew from the 2015 nuclear deal and reinstated sweeping sanctions on the country.
Iran scaled back some of its commitments under the landmark accord last month, including on the amount of low enriched uranium it is allowed to stockpile, after Trump ended exemptions from U.S. sanctions for countries still buying Iranian crude.
The Trump administration hopes additional sanctions on Iran will force the country to negotiate, with U.S. National Security Adviser John Bolton saying Washington would be prepared to go further in order to get Iran to the table.
The U.S. has also bolstered its military presence in the Middle East and blacklisted Iran's Revolutionary Guard as a terrorist organization.