'They have to do that,' Trump says
Trump did not specify what he meant by referring to the nuclear pact signed by Tehran and international powers in 2015 that put far-reaching curbs on the Islamic Republic's nuclear program in exchange for sanctions relief.
"They have to do that," he said, adding, "we will see what happens."
U.S. Ambassador to the UN Nikki Haley told the Security Council Thursday that Iran was the "chief culprit" for conflicts in the Middle East, along with its "partner militia" Hezbollah.
"Iran and Hezbollah conspire together to destabilize the Middle East, and their actions are expanding. For decades, they have committed terrorist acts across the region," Haley said, and are propping up "Bashar al-Assad's brutality".
"While this Council has paid too little attention to this growing menace, the United States will not," Haley added, promising to "speak up" and "act against their lawlessness".
The comments come one day after Trump's top diplomat, Rex Tillerson, slammed Iran's "alarming and ongoing provocations", announcing a "comprehensive review" of U.S. policy toward the Middle East country.
The statement came hours after the State Department confirmed Iran continued to comply with the terms of the deal.
Tillerson said the agreement "fails to achieve the objective of a non-nuclear Iran", but he stopped short of threatening to terminate the deal or punish Tehran with more sanctions.
He nevertheless added that the Trump administration had "no intention of passing the buck to a future administration on Iran".
Trump has long been a critic of the agreement, repeatedly taking aim at its terms and the negotiation process as one of the worst he's ever seen -- a claim he repeated Thursday. While campaigning he threatened to do away with the accord but has been short on specifics after assuming office three months ago.
"They are not living up to the spirit of the agreement. I can tell you that," Trump said. "It shouldn’t have been signed."