The European Union approved a ban on oil imports from Iran, overcoming misgivings about the economic hardship of its members to take its strongest measures yet to press Tehran into concessions on its nuclear program.

News of a coming embargo by Iran's largest oil-export market shocked the country's troubled economy. Iran's currency, the rial, fell 10% to a record low on Monday, while gold prices rose.

The ban is set to take effect on July 1, following a review to ensure the weaker EU economies can find, and afford, new sources of oil. The EU also agreed to freeze the assets of Iran's central bank, the conduit for the country's oil revenue, and ban trade with its petrochemical industry.

"Our message is clear. We have no quarrel with the Iranian people," the leaders of France, Germany and the U.K. said. "But the Iranian leadership has failed to restore international confidence in the exclusively peaceful nature of its nuclear program. We will not accept Iran acquiring a nuclear weapon."

Iran's Deputy Foreign Minister Abbas Araghchi said sanctions made Iran's conflict with the West tougher to resolve.