Speaking at his weekly press conference on Monday, Esmaeil Baqaei said there should be no ambiguity regarding the parties involved in the current negotiations.
"We are not holding any negotiations with the United States at present," he said, explaining that the ongoing talks are exclusively between Iran and Oman and are focused on reaching an understanding on the safe passage of ships through the Strait of Hormuz.
Baqaei said Tehran is working, in consultation with Muscat, to determine a temporary arrangement that would ensure maritime safety in the strategic waterway.
He stressed that the negotiations are strictly bilateral between the two littoral states, adding that while other parties may play either a constructive or destructive role, the issue itself concerns only Iran and Oman, with any future developments to be decided later.
The spokesman rejected claims that the Strait of Hormuz had been disrupted because of differences between Tehran and Muscat, saying the situation arose as a result of the US aggression that began on February 28.
He added that as long as the US naval blockade and Washington's hostile actions and violations continue, no change should be expected in the status of the strait.
Commenting on reports that China is mediating between Iran and the US, Baqaei said Pakistan remains the mediator on issues related to Tehran and Washington, with Qatar also playing a supporting role.
He said Iran enjoys friendly relations with China and that Beijing shares Tehran's concerns over the escalating hostile behavior of the US and growing regional insecurity. While Chinese officials are using their good offices to help prevent further escalation, he said reports claiming that China has become a new mediator are incorrect.
The spokesman also dismissed claims that Pakistani and Qatari representatives are participating in negotiations between Iran and the US.