Ayatollah Ali Khamenei, the supreme leader, said the “Death to America” slogan is eternal. New anti-American billboards in Tehran include a mockery of the Iwo Jima flag-raising photograph that symbolized Marine sacrifice in World War II. And an Iranian knockoff version of K.F.C., the chicken chain widely associated with the United States, was summarily closed after two days.

“It feels like a witch hunt,” said one Iranian-American businessman in Tehran, who dared not speak for attribution over fear for his safety. “It’s pretty scary.”…

Now, as the autumn leaves are falling in Tehran, there are no signs that bolder changes are coming. On the contrary, a backlash appears to be underway, promoted by Mr. Rouhani’s hard-line adversaries in the government who are deeply skeptical of the United States and its allies.

The backlash comes as Iran is preparing for parliamentary elections in February that constitute a litmus test of Mr. Rouhani’s policies. It seems that hard-liners, using the intelligence unit of the Revolutionary Guards Corps, have started rounding up journalists, activists and cultural figures, as a warning that the post nuclear-deal period cannot lead to further relaxation or political demands.