Secretary of State Mike Pompeo told the UN Security Council that the clock was ticking on a resolution restricting weapons sales to Iran that is due to end in October 2020.
Pompeo warned that the expiration of provisions in Security Council Resolution 2231 would also see a travel ban on a key Iranian commander lifted.
"Time is drawing short to continue this activity of restricting Iran's capacity to foment its terror regime," he said.
"The international community will have plenty of time to see how long it has until Iran is unshackled to create new turmoil, and figure out what it must do to prevent that from happening," Pompeo added.
The resolution was passed as part of the Joint Comprehensive Plan of Action, otherwise known as the Iran nuclear deal which the US, Russia, China, France, Germany and Britain agreed with Tehran in 2015.
The landmark deal was designed to curb Iran's nuclear programme in exchange for sanctions relief.
President Donald Trump unilaterally withdrew the US from the deal last year and reinstated economic sanctions, sending tensions between Washington and Tehran soaring.
When the resolution expires next year, travel restrictions on Qasem Soleimani, the commander of Iran's Quds Force, which operates abroad, and 23 other Iranians will be lifted.
"We believe that the UNSC has an important role to play to ensure that the arms embargo and the travel ban are continued," Brian Hook, the US Special Representative for Iran told reporters in New York ahead of Pompeo's remarks.
Trump's administration is currently pursuing a "maximum pressure" campaign designed to force the Islamic republic to limit its nuclear programme and military activities.
Iran has responded by suspending some of its commitments under the nuclear deal.
The situation has threatened to spiral out of control with ships attacked, drones downed and oil tankers seized.
Meanwhile, the US has been struggling to piece together an international coalition to protect cargo ships travelling through the Gulf.
Allies are concerned about being dragged into conflict with Iran while European countries are trying to keep the nuclear deal alive.
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