TEHRAN — The man stood outside the notorious Evin Prison in Tehran on Sunday, his hands deep in his pockets as snow continued to fall. His son Majid had been inside the prison for over a week, after being arrested during the largest antigovernment demonstrations Iran has seen in years.

“My wife and I are here every day,” said the man, who gave only his first name, Hossein. “I don’t want trouble. I just want my son released.”

Majid, a 32-year-old employee at a telecommunications company, calls from prison daily. He had not been protesting at all, his father insists, and was arrested by mistake.

Members of Iran’s ruling establishment have taken turns assigning blame for the protests in more than 80 cities that have resulted in at least 21 deaths and shined a light on the country’s declining economic conditions, corruption and a lack of personal freedom. Some have accused foreign “enemies,” including the United States, Israel and Saudi Arabia, of organizing and financing the movement.