THAT'S WHY NOW:

In repeated meetings during the week, Mr. Rouhani and his foreign minister, Mohammad Javad Zarif, said the government's financial condition was far more dire than the previous president, Mahmoud Ahmadinejad, had let on.

Mr. Rouhani and Mr. Zarif did not publicly specify the severity of the cash squeeze. But Western economists believe the crisis point may be much closer than previously thought, perhaps a matter of months. Iran news outlets have reported that the government owes billions of dollars to private contractors, banks and municipalities.

Because of the sanctions, oil sales, which account for 80 percent of the government's revenue, have been cut in half. While Mr. Ahmadinejad had asserted that Iran had $100 billion in foreign exchange reserves, the total had shrunk to $80 billion by mid-2013, according to a new study by Roubini Global Economics, a research firm based in New York, and the Foundation for Defense of Democracies, a Washington group that advocates strong sanctions against Iran.

But even that vastly overstates the amount readily available to Iran. Three-quarters of the $80 billion is tied up in escrow accounts in countries that buy Iranian oil -- the result of an American sanctions law that took effect in February. Under that law, the money can be spent only to buy products from those countries.

Even gaining access to the remaining $20 billion is difficult -- it has to be physically moved in cash because of Iran's expulsion from the global banking network known by its acronym Swift, which had allowed the money to be transmitted electronically.

"They can't repatriate the money back to Iran," said Mark Dubowitz, the executive director of the Foundation for Defense of Democracies. "This is the dilemma Iran finds itself in."

The sanctions pose other problems. Unable to arrange simple financing for business deals, executives are forced to transfer suitcases of cash through street-level money changers to shady bankers abroad. This is not only costly, with middlemen exacting fees every step of the way, but also dangerous, the cash making a tempting target for thieves.

Lower-level officials here and businesspeople are even more alarmed than the leadership, with some saying Iran's economy is already on the verge of collapse.

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