The United States is preparing to increase oil sanctions against Iran over its nuclear programme.
US President Barack Obama has issued a statement saying there is enough oil on the world market to allow a significant reduction in purchases from Iran.
He added that after June, countries that buy oil through Iran's central bank will face US sanctions.
Oil markets remain tight, the White House said. But surging petrol prices have become a major issue in the presidential election campaign.
In his decision, required by a sanctions law he signed in December, Mr Obama said increased production by some countries as well as "the existence of strategic reserves" helped him come to the conclusion that sanctions can advance.
"I will closely monitor this situation to assure that the market can continue to accommodate a reduction in purchases of petroleum and petroleum products from Iran," he said.
Mr Obama had been expected to press on with the sanctions to press Iran to curb its nuclear programme, which the West suspects is a cover to develop atomic weapons but which Iran says is purely civilian.
The mention of government-controlled stockpiles may further stoke speculation that major consumer nations are preparing to tap their emergency stores this year.
"A series of production disruptions in South Sudan, Syria, Yemen, Nigeria, and the North Sea have removed oil from the market," the White House said.
France is in talks with the United States and Britain on a possible release of strategic oil stocks to push fuel prices lower, French ministers said on Wednesday.
Senior Obama administration officials told reporters that the US views releasing emergency stocks as an option, but said no decision has been made on specific actions.
