Trump wrote in a letter to House Speaker Mike Johnson and Senate President Pro Tempore Chuck Grassley that "hostilities that began on February 28 have ended," saying there has been no shelling since April 7.
In the United States, only Congress can declare war. The president can only authorize military operations for up to 60 days after Congress is informed of an operation - a deadline that passed on May 1.
Earlier on Friday, Iran submitted a new negotiation proposal to the US via Pakistan, the mediator, according to Iranian media.
That proposal was dismissed by Trump.
"I'm not happy with what they're offering," he told reporters.
