Media have reported that the United States has approached Russia in an attempt to hold negotiations with Tehran at the level of the countries' foreign ministries.
Mousavi, however, said that Iran was not engaged in any talks with Washington at the moment, the outlet reported.
Tehran wants the United States to first lift its unilateral economic sanctions on Iran before any negotiations can take place.
Meanwhile, Iranian Foreign Minister Mohammad Javad Zarif went to New York on Saturday to participate in the meeting of the United Nations Economic and Social Council.
US-Iranian relations have been particularly tense these past few months following attacks on oil tankers in the Persian Gulf region. Washington has accused Tehran of organising attacks on the vessels, while Iran categorically refutes the allegations.
The downing of a US surveillance drone off Iran's coast in late June fueled tensions between the two countries to a point where the United States was about to strike the Middle Eastern country.