US President Donald Trump says he's "not at all" concerned about provoking tensions with Iran. But Iran's Foreign Minister is warning the US to "be cautious!" Tehran and Washington are ramping up a war of words, just weeks before the US is set to re-impose sanctions. CGTN White House correspondent Nathan King reports.  

Tehran and Washington are ramping up their rhetoric as the Trump administration pushes its new tough line against Iran. In front of a group of Iranian-Americans this past weekend, the U.S. secretary of state outlined plans to re-impose financial and energy sanctions.

MIKE POMPEO US SECRETARY OF STATE "We have an obligation to put maximum pressure on the regime's ability to generate and move money and we will do so. At the center of this campaign is the re-imposition of sanctions on Iran's banking and energy sectors. As we have explained over the last few weeks, our focus is to work with countries importing Iranian crude oil to get imports as close to zero as possible by November 4th. Zero."

Sanctions will re-start next month. China, Russia and the EU, who are working to save the 2015 Iran nuclear deal, have all vowed to continue trading with Iran- but given U.S. opposition, difficult choices may have to be made.

On Sunday, Iranian President Hassan Rouhani warned President Trump not to "play with the lion's tail".

HASSAN ROUHANI IRANIAN PRESIDENT "We do not want to go into a war with them. But they must understand well that war with Iran is mother of all wars. They have to understand it very well that peace with Iran is mother of all peace."

Upping the tensions, President Trump responded by tweeting: "NEVER, EVER THREATEN THE UNITED STATES AGAIN OR YOU WILL SUFFER CONSEQUENCES THE LIKES OF WHICH FEW THROUGHOUT HISTORY HAVE EVER SUFFERED BEFORE."

Backing his boss, U.S. National Security Advisor John Bolton said if Iran does anything negative, it will quote: "Pay like few countries have ever paid before."

NATHAN KING WASHINGTON DC "So could the escalation of threats lead to high-level talks like we saw with the DPRK? There's no sign of that at least for now. The Trump administration has long advocated a tough line on Iran - even calling for regime change. Nathan King, CGTN at the White House."