Iran's foreign minister says Tehran could resume full nuclear operations if the West withdraws from a pact that is to be finalized in June.
Mohammad Javad Zarif said Iran has the power to take "corresponding action" and "will be able to return" its nuclear program to the same level if the other side fails to honor the agreement.
Zarif, Iran's chief nuclear negotiator, was responding to a question on a talk show on Iranian state TV late on April 4.
Commentators say his remarks appear aimed at reassuring conservative Iranian politicians who strongly oppose the deal reached on April 2 in Switzerland.
Zarif told the TV audience that Iran had negotiated from a position of strength to secure a good preliminary deal.
Iran and six world powers announced a framework for a deal to curb Iran's nuclear program in return for lifting Western sanctions.
They face a June 30 deadline to finalize the pact.
Zarif said Iran would stick to its promises so long as the West also did so, and suggested a deal could open the door to more productive relations with the international community.
"Inside the negotiation room we are honest and outside the negotiation room we are honest," he said.
The White House has said it is confident final details on a deal to curb Iran's nuclear program can be worked out.
President Barack Obama spoke on April 3 with the four top leaders in the U.S. House of Representatives and the U.S. Senate to discuss the framework agreement announced on April 2 by negotiators in Switzerland.
"We feel good," White House spokesman Eric Schultz said. "There's a lot of work to be done, but we are confident we can get those details in place."
The White House also tried to ease Israeli concerns over the deal.
Prime Minister Benjamin Netanyahu said on April 3 the Jewish state demanded that any final agreement with Iran acknowledge his state's right to exist.
Asked about that demand, Schultz said Obama "would never sign onto a deal that he felt was a threat to the state of Israel."
Meanwhile, Iranian President Hassan Rohani, in a televised speech, hailed the framework as "a first step towards productive interactions with the world."
Schultz said he understood Tehran's need to sell the deal to Iranians but that the United States sees it as one focused on Iran's nuclear program.
"The concerns we have with Iran outside of the nuclear program remain just as vibrant ... yesterday as they are today."