TEHRAN — The sense of crisis in Iran runs deep and wide. The economy is in free fall. The currency is plummeting. Rising prices are squeezing city dwellers. A five-year drought is devastating the countryside. The pitched battle between political moderates and hard-liners is so perilous that there is even talk of a military takeover.

Now, the lifeline offered by the 2015 nuclear deal, which was supposed to alleviate pressure on Iran’s economy and crack open the barriers to the West, is falling apart, too: President Trump announced Tuesday that he was withdrawing the United States from the agreement, which he called a “disastrous deal.”

The chief loser will be the country’s moderate president, Hassan Rouhani, who now looks weakened, foolish and burned for the risk he took in dealing with the Americans.

Addressing the nation on live television after Mr. Trump’s announcement, Mr. Rouhani said Iran would take no immediate action to restart uranium enrichment and that it would negotiate with the other parties to the agreement, Britain, China, France, Germany and Russia.