Iranian Foreign Minister Mohammad Javad Zarif lashed out at Sen. Tom Cotton on Thursday after the Arkansas Republican challenged him to a debate on the U.S. Constitution, accusing the senator of engaging in "smear" tactics.

Cotton issued the challenge in response to comments made by Zarif at New York University on Wednesday, in which he declared that U.N. sanctions on Iran would be lifted if there is a nuclear accord, "whether Sen. Cotton likes it or not."

Power Line noted that in his remarks, Zarif declared the United States would be forced to lift sanctions by U.N. resolutions and said Congress would be powerless to stop President Barack Obama from doing this.

"The American president is bound by international law, whether they like it or not," the Iranian diplomat said.

Zarif added that Obama "will have to stop implementing all the sanctions, economic and financial sanctions that have been by executive order and congressional. However he does it, that's his problem."

Cotton responded to Zarif on social media, tweeting that, "I hear you called me out today… If you're so confident, let's debate the Constitution," Politico reported.

Cotton then offered Zarif the opportunity to meet in Washington at the "time of your choosing to debate Iran's record of tyranny, treachery, & terror."

After issuing the challenge, Cotton followed up with a tweet in which he said he would "understand" if the foreign minister declined his challenge because "after all, in your 20s, you hid in the US during Iran/Iraq war while peasants & kids were marched to death."

Cotton added that it was not a "badge of courage" for Zarif "to hide in US while your country fought war to survive — but shows cowardly character still on display today."

Zarif finally responded to Cotton on Thursday, telling him that what is needed today is "serious diplomacy" instead of a "macho personal smear."

Zarif's overall attitude "highlights the necessity for Congressional oversight" and "vindicates" the 47 GOP senators who signed Cotton's recent letter to Iranian officials reminding them of Congress's legal authority, Power Line said.

"A future president most certainly can extricate the U.S. from a disastrous executive agreement, assuming it is not too late. And Congress can exercise its authority under the Constitution in a variety of ways, including voting to re-impose sanctions."

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