TEHRAN—Iran has executed a wrestler and alleged murderer whose life President Trump had asked the country’s leaders to spare, Iranian state TV reported.

“The retaliation sentence against Navid Afkari, the killer of Hassan Turkman, was carried out this morning in Adelabad prison in Shiraz,” the chief justice of Fars province, Kazem Mousavi, said Saturday, according to state TV.

The 27-year-old’s case had drawn the attention of a social-media campaign that portrayed him and his brothers as victims, targeted for participating in protests against Iran’s Shiite theocracy in 2018. Authorities accused Mr. Afkari of stabbing an employee of a water-supply company in the southern city of Shiraz during the unrest.

Iran televised the wrestler’s confession last week. It resembled hundreds of others aired over the past decade in the Islamic Republic that have raised suspicions of coercion.

The case revived a call in Iran for an end to the death penalty.

Those expressing support for Mr. Afkari included imprisoned human-rights lawyer Nasrin Sotoudeh, nearly a month into a hunger strike over conditions at Tehran’s Evin prison amid the coronavirus pandemic. Earlier this month, Mr. Trump tweeted his concerns about the case, closing, “To the leaders of Iran, I would greatly appreciate if you would spare this young man’s life, and not execute him. Thank you!”

Iran state TV responded with a report on the case that lasted nearly 11 minutes. It included footage of blurred police documents, of the weeping parents of the slain man and of Mr. Afkari on the back of a motorbike, saying he had stabbed Mr. Turkman in the back. He didn’t explain why, and the report merely said it was a “personal dispute.” It said Mr. Afkari’s cellphone had been in the area and showed surveillance footage of him walking down a street, talking on a phone.

Iran’s semiofficial Tasnim news agency dismissed the Trump tweet in a feature story, saying that American sanctions have hurt Iranian hospitals already burdened by the coronavirus pandemic.

“Trump is worried about the life of a murderer while he puts many Iranian patients’ lives in danger by imposing severe sanctions,” the story said.