Trump came into office vowing to take a hard line on Iran and scrap the Obama-negotiated nuclear deal of 2015, a promise he fulfilled in May.
Trump tweeted Sunday that if Iran threatened the U.S.it would "SUFFER CONSEQUENCES THE LIKES OF WHICH FEW THROUGHOUT HISTORY HAVE EVER SUFFERED BEFORE". "The Americans", Rouhani said, "need to realize that making peace with Iran is the mother of all peaces, and waging war against Iran is the mother of all wars".
He added that Trump "is letting the Iranian president know there's a new sheriff in town".
Speaking on Sunday to high-ranking diplomats in Tehran, Rouhani warned Trump that "war with Iran will be the mother of all wars" and cautioned Washington not to "play with fire".
"I withdrew the United States from the awful one-sided Iran nuclear deal", he said.
In a tweet on late Sunday, Trump warned his Iranian counterpart Hassan Rouhani that if Tehran threatened the USA again, it would suffer "consequences the likes of which few have ever suffered before".
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We hope that the two sides will step up communication and expand cooperation. "It is a matter of principle", he said. China's efforts in abiding by the WTO rules and fulfilling its commitments have gained worldwide recognition.
Later Monday morning, national security adviser John Bolton said Trump told him that "if Iran does anything at all to the negative, they will pay a price like few countries have ever paid before".
Iranian Islamic Revolutionary Guard Corps Commander Mohammad Bagheri also vowed to implement a "strong, unimaginable and regrettable" response from Tehran.
Democrats have expressed alarm about Trump's Iran bluster. But that approach faces an uncertain future now that Washington has withdrawn from the nuclear deal with Iran, and quickly moved to use its tremendous economic leverage to pressure all other nations to stop importing Iranian oil, the life-blood of the Iranian economy. Before the nuclear deal, the U.S. was punishing Iran with the help of allies and even some adversaries.
Following the US's unilateral exit, the Trump administration has been seeking to have other countries follow suit by raising the spectre of snapped-back sanctions which would punish businesses and governments from activities that were allowed under the agreement.
He tempered these remarks on Tuesday, saying: "We're ready to make a real deal" with Iran.
He said that the US Broadcasting Board of Governors was going to attempt to circumvent Internet censorship in Iran by creating a slew of Farsi media outlets (including television, radio, digital and social media) to show "ordinary Iranians inside Iran and around the globe [that] America stands with them".