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.