The White House said it is prepared to talk one-on-one with Iran to find a diplomatic settlement to the impasse over Tehran's reported pursuit of nuclear weapons, but there is no agreement now to meet.
National Security Council spokesman Tommy Vietor said that President Barack Obama has made clear that he will prevent Iran from getting a nuclear weapon and will do whatever's necessary to prevent that from happening.
Mr Vietor said Iran must come in line with its obligations, or else faced increased pressure.
"The onus is on the Iranians to do so, otherwise they will continue to face crippling sanctions and increased pressure," Mr Vietor said in a statement.
He noted that efforts to get Iran back to the table with the five permanent members of the UN Security Council and Germany - the so-called P5+1 - continue.
Iran has been a recurring issue in the presidential election campaign and Mr Vietor's statement was released shortly after The New York Times reported that the US and Iran have agreed in principle for the first time to negotiations.
The paper said Iran has insisted the talks wait until after the November 6 election.
Mr Vietor, however, denied that any such agreement had been reached.
"It's not true that the United States and Iran have agreed to one-on-one talks or any meeting after the American elections," he said.
"We continue to work with the P5+1 on a diplomatic solution and have said from the outset that we that we would be prepared to meet bilaterally."