EU foreign policy chief Catherine Ashton said Tuesday that European officials met last weekend with aides to Iran's top nuclear negotiators, Saeed Jalili. She said she plans to meet directly with Jalili soon.
That is seen as a key step in the resumption of talks between Iran and world powers over Tehran's disputed nuclear program. The West fears Iran may be trying to develop nuclear weapons, a charge Tehran denies.
Clinton said the diplomatic window of opportunity for Iran wouldn't stay open forever. Speaking alongside Ashton in Bosnia, she said Iran must do more to end its international isolation.
"Our message to Iran is clear: The window remains open to resolve the international community's concerns about your nuclear program diplomatically and to relieve your isolation, but that window cannot remain open indefinitely. Therefore, we hope that there can be serious good-faith negotiations commenced soon," Clinton said.