Iranian President Hassan Rohani has said he is seeking expanded, wartime executive powers to deal with an "economic war" being waged against the country by the United States.

Relations between Tehran and Washington have plummeted since last year when U.S. President Donald Trump pulled Washington out of the 2015 nuclear deal that curbed Iran's nuclear program in exchange for relief from crippling economic sanctions.

Since then, Washington has stepped up its rhetoric and reimposed sanctions.

There have been growing concerns of a possible military conflict with the United States, which has warned of "imminent threats" from Tehran, a claim Iran has denied.

Rohani cited the devastating war with Iraq from 1980-88, when a Supreme Council of War was able to bypass other branches to make decisions regarding the economy and the war effort.

"We need such powers today," Rohani said late on May 20, according to Iran's official IRNA news agency.

The president also said that he favored talks and diplomacy to deescalate tensions with Washington but not under the current conditions.

"Today's situation is not suitable for talks and our choice is resistance only," IRNA quoted Rohani as saying.

On May 20, Trump said that Iran would be met with "great force" if it attempted anything against U.S. interests in the Middle East.

He also said that if Tehran wants to negotiate, it will have to take the first step.

"Iran will call us if and when they are ever ready. In the meantime, their economy continues to collapse - very sad for the Iranian people!" the U.S. president tweeted.