US State Department spokesman Richard Boucher told reporters that US officials were “not engaged in or not seeking talks with Iran regarding its nuclear programme”.
Asked about a report that Washington had rejected Iranian overtures for bilateral talks, Boucher said the US policy was to support ongoing efforts by the International Atomic Energy Agency (IAEA).
The United States has amassed pressure on Iran to allow tougher inspections on its nuclear programme.
It accuses the Islamic republic of using its civilian programme as a covert to develop nuclear weapons.
Tehran denies the accusations and says its programme aims at generating electricity for its fast-growing population.
"Iran's programme is of concern to the international community, not just the United States," Boucher said.
"We look to Iran to respond to the requests from the International Atomic Energy Agency, for them to rectify the outstanding problems and answer unresolved questions," he added.
Citing unnamed officials, The Financial Times reported earlier Tuesday that Iranian Ambassador to the UN Mohammad Javad Zarif had signalled his country’s willingness to discuss the nuclear issue with Washington.
Tehran's readiness to talk with the United States was also conveyed to US officials by Swiss Ambassador to Iran Tim Guldimann, the paper said.
Switzerland represents US interests in Iran.