Iran, the five permanent members of the U.N. Security Council plus Germany, began a third round of negotiations regarding Tehran's nuclear program this week in Moscow.
Before the meeting, Iranian President Mahmoud Ahmadinejad told German newspaper Frankfurter Allgemeine Zeitung Iran was "willing to take a positive step" to allay international concerns about the nuclear program.
Iran maintains the right to pursue a civilian nuclear program under the terms of international mechanisms. Some countries, however, say Iran is using that justification as cover for a nuclear weapons program.
Michael Mann, a foreign policy spokesman for the European Union, told Bloomberg News that the assurances weren't enough.
"All the sanctions that are supposed to come into force on July 1 will come into force on July 1," he said. "We've taken a political decision that this is an important measure to put pressure on the Iranian regime."
An embargo on Iranian oil goes into force July 1 in the European Union. Iran is the No. 2 oil producer among members of the Organization of Petroleum Exporting Countries.