The U.S. State Department said Thursday that Washington's policy on Iranian oil sanctions remains the same, and there will be no exemptions for any country.

The U.S. ended oil sanctions waivers for countries that were still purchasing Iranian oil earlier this month, giving them time to wean off Tehran's supply and obtain other sources of oil after reinstating sanctions back in November.

The sanctions were part of the Trump administration's pressure campaign on Iran through both economic pressure and military deployments to subdue Iran's activities abroad.

"We're going to zero, and of course there are no extensions of these waivers, and that remains our policy," State Department spokeswoman Morgan Ortagus told reporters.

She was responding to a question on reports that China and India were allowed to continue to take delivery of oil shipments from Iran as long as the purchases were made prior to the expiration of the sanctions waivers.

Ortagus told reporters that the U.S. pressure campaign has been successful in curbing Iran's influence in the Middle East.

"We see the compliance with U.S. sanctions regarding Iran are at large one of the most successful things that this administration and the State Department has done," she added.

Ortagus also welcomed the convening of an emergency meeting of Gulf state leaders in Saudi Arabia aimed at discussing Iranian threats to the region.

In early May, the UAE claimed that four vessels, including two oil tankers, had been targeted in "sabotage attacks" near its territorial waters.

Days later, Saudi Arabia said armed drones had attacked two pumping stations on the East-West Pipeline, which carries oil from the kingdom’s Eastern Province to the Port of Yanbu.

Riyadh has since accused Yemen’s Houthi rebel group, which is known to be close to Iran, of carrying out the attack.