Iranian Foreign Ministry spokesman Abbas Mousavi said Iran has not officially received any proposal about the United States taking part in the talks between Iran and the 4+1 group.
Iranian news agency IRNA also quoted Mousavi as saying that he has heard about the "freeze against freeze" plan but did not elaborate.
This is said to be a plan offered by French President Emmanuel Macron, which suggests Iran should give up the gradual suspension of its obligations under the 2015 nuclear agreement, while the US lifts some of its sanctions against Tehran temporarily.
Macron's envoy Emmanuel Bonne held a meeting on Wednesday, July 10 in Tehran with Iran's Security Chief Ali Shamkhani. But at this point it is not clear if the two sides made any progress in reducing tensions or finding a compromise.
Asked if the French official's visit to Tehran was coordinated with Washington, Mousavi said: "It is up to them. We do not have any secret. What we want is the implementation of the existing nuclear deal that they have violated."
Meanwhile, the US special representative for Iran, Brian Hook, told Al Arabiya that Iran has rejected diplomacy “too many times,” and that “right now, there are no back-channel talks between the US and Iran.”