The U.S. State Department said on Tuesday that it has been pushing countries to stop importing oil from Iran by November.
The United States has been pushing allies to stop oil imports from Iran by Nov. 4, a senior U.S. State Department official told reporters in a background briefing on Tuesday morning.
The official, speaking on condition of anonymity, also said that currently the United States was "not granting waivers" to any country which was in business with Iran.
When asked how related countries responded, the official said that there was "some kind of effect achieved."
Following Trump's decision to quit the historic Iran nuclear pact on May 8, the United States vowed to re-impose sanctions lifted under the accord against Tehran and inflict punishments like secondary sanctions on nations that have business links with Tehran.
Firms that were doing business in Iran were given up to 180 days to wind up investments. Otherwise, they risk huge fines.
Washington's withdrawal from the landmark Iran nuclear deal was widely criticized across the world. And some of its major European allies have been working to prevent the 2015 deal from falling apart.
A senior official from Iran's Foreign Ministry said Saturday that European countries will soon offer a package to protect Iran's interests in accordance with the 2015 deal, official IRNA news agency reported.
Earlier this month, foreign ministers and economic ministers from France, Germany and Britain urged Washington to exempt European companies engaged in trade with Tehran after Washington threatened to impose tough sanctions on the Islamic Republic and all countries doing businesses with Tehran.
Oil prices rebounded strongly on Tuesday following the message from the U.S. State Department.