The trio of European nations plus the US, Russia and China — the so-called E3+3 group — has sought to negotiate with Iran, which denies it seeks a bomb.
Ministers from the six nations met in New York on Thursday and again called on Iran to “urgently” show the proof that its intentions are peaceful.
Experts from the six are due to meet in London soon to “determine our negotiating position for any further meeting with the Iranians,” the first senior official said.
EU High Representative of the Union for Foreign Affairs and Security Policy Catherine Ashton said she would be contacting Iran to determine whether more negotiations should be held.
Alongside the sanctions and talks, the US and Europe have also stepped up pressure on Iran over its support for Syrian President Bashar al-Assad and militant groups in the region.
The US is pushing Gulf states to develop missile defense plans, amid what they see as a rising threat from Iran, US officials said.