Two years ago there was talk of whether, with the nuclear dispute behind them, the United States and Iran might cooperate against the Islamic State and strike a deal over Syria. Traditional Sunni allies of the United States like Saudi Arabia wondered if Washington was about to pivot toward Iran, which has a predominantly Shiite population, for the first time since the Shah’s fall.

Indeed, the deal was seen as a major gamble by the Obama administration. Over time, many officials thought, the two countries would use it as a foundation for building a larger relationship.

Today that foundation is crumbling. Administration officials say the debate over whether to ultimately scrap the accord continues, though they acknowledge that doing that would free Iran to resume enrichment of uranium and reprocessing of plutonium, the exact activities the deal sharply limits.

On Sunday, Iran disclosed that it had been holding Xiyue Wang, an American who is a Princeton University doctoral candidate in history, for nearly a year and has sentenced him to 10 years in prison on spying charges. The disclosure shocked Mr. Wang’s colleagues at Princeton, who described Iran’s action as a colossal error. The incarceration of Mr. Wang, 37, also threatened to chill academic exchanges between Iran and the United States.

The reception Mr. Zarif receives now in Washington could not be more different than it was 24 months ago. He and Mr. Kerry developed a close rapport, even if it was often punctuated by shouting matches. But Mr. Zarif said he had never spoken with Mr. Kerry’s successor, Rex W. Tillerson.

“I haven’t asked for a meeting, and I don’t think I will,” he said.

Mr. Zarif said that if conversations do begin anew with the United States, they will be limited to the nuclear deal — and American compliance. But he did not sound hopeful, adding that Iran had no intention of renegotiating.