WASHINGTON — US President Donald Trump said on Monday Iran would be met with "great force" if it attempted anything against US interests in the Middle East, adding that Tehran has been very hostile toward Washington.

Trump told reporters as he departed the White House for an event in Pennsylvania that he was willing to have talks with Iran "when they're ready" but no discussions were going on now.

Trump's remarks came despite pleas from Tehran on Monday for the United States to treat Iran with respect, not threats of war, in response to the US leader's comments on Sunday that stoked concerns about a potential US-Iran conflict.

"With Iran, we'll see what happens," Trump told reporters on Monday. "But they've been very hostile. They've truly been the No.1 provocateur of terror."

"I think Iran would be making a very big mistake if they did anything. If they do something, it will be met with great force but we have no indication that they will," Trump said.

"We'll have no choice," he added.

Trump warned Iranian leaders not to call for talks unless they were prepared to negotiate.

But in a sign of brewing confrontation a year after Washington quit a 2015 nuclear deal with Iran and reimposed sanctions on it, Tehran announced a fourfold increase in its rate of production of low-grade uranium enrichment. — Reuters