On Sunday, the U.S. government said that no exchange of prisoners between Washington and Tehran was agreed between the two countries.
This comes after Iranian state television said that Tehran would free four Americans accused of spying in exchange for four Iranians held in the United States and the release of $7 billion in frozen Iranian funds.
The state TV, quoting an Iranian official, also said British-Iranian national Nazanin Zaghari-Ratcliffe would be released once Britain had paid off a debt on military equipment owed to Tehran.
Iran and world powers are holding talks to revive the 2015 nuclear accord that Washington abandoned three years ago.
Iranian officials told Reuters last month that an interim deal could be a way to gain time for a lasting settlement that involved unfreezing Iranian funds blocked under U.S. sanctions.
"An informed source says Biden administration has agreed to release four Iranian prisoners jailed for bypassing U.S. sanctions in exchange for four American 'spies'," the Iranian state TV report said on Sunday.
"Release of Nazanin Zaghari in exchange for UK's payment of its 400 million pound debt to Iran has also been finalized. The source also said the Biden administration has agreed to pay Iran $7 billion," it said.
In Washington, State Department spokesman Ned Price told Reuters: "Reports that a prisoner swap deal has been reached are not true".
"As we have said, we always raise the cases of Americans detained or missing in Iran. We will not stop until we are able to reunite them with their families."
Ron Klain, White House chief of staff, also denied the report. "Unfortunately, that report is untrue. There is no agreement to release these four Americans," Klain said on CBS "Face the Nation".
Tehran and the powers have been meeting in Vienna since early April to work on steps that must be taken, touching on U.S. sanctions and Iran's alleged breaches of the 2015 deal, to bring Tehran and Washington back into full compliance with the accord.
Iran says $20 billion of its oil revenue has been frozen in countries like South Korea, Iraq, and China under U.S. sanctions since 2018.
U.S. national security adviser Jake Sullivan, speaking on ABC's "This Week" on Sunday, said no deal had been reached with Iran in Vienna.
"There is still a fair distance to travel to close the remaining gaps," he said. "And those gaps are over what sanctions the United States and other countries will rollback. They are over what nuclear restrictions Iran will accept on its program to ensure that they can never get a nuclear weapon."