WASHINGTON — After careful analysis of oil prices and months of negotiations, President Obama on Friday determined that there was sufficient oil in world markets to allow countries to significantly reduce their Iranian imports, clearing the way for Washington to impose severe new sanctions intended to slash Iran’s oil revenue and press Tehran to abandon its nuclear ambitions.

The White House announcement comes after months of back-channel talks to prepare the global energy market to cut Iran out — but without raising the price of oil, which would benefit Iran and harm the economies of the United States and Europe.

Since the sanctions became law in December, administration officials have encouraged oil exporters with spare capacity, particularly Saudi Arabia, to increase their production. They have discussed with Britain and France releasing their oil reserves in the event of a supply disruption.

And they have conducted a high-level campaign of shuttle diplomacy to try to persuade other countries, like China, Japan and South Korea, to buy less oil and demand discounts from Iran, in compliance with the sanctions.