By Pooya Stone

The United States warned Iran it is taking Tehran's threats seriously and will hold it accountable if it compromises the safety of any American citizen.

The comments came in a tweet from US State Department spokeswoman Morgan Ortagus on Saturday, after Iran announced sanctions against American Mark Dubowitz and his think tank – the Foundation for Defense of Democracies – for what it called "US economic terrorism".

"The outlaw regime in Iran issued a threat today against @FDD, an American think tank, and its CEO. The U.S. takes the regime's threats seriously. We intend to hold Iran responsible for directly or indirectly compromising the safety of any American," Ortagus said.