The letter to Ayatollah Ali Khamenei represents the latest daring challenge to the Islamic leadership. It called the attacks a sign of weakness in the ruling system.
It urges Khamenei to order arrests for the hard-line crackdown, which was increased after protesters began chanting slogans against the supreme leader. The Greenroad Web site posted the letter on Monday.
At least eight people died during clashes across Iran last month, including a nephew of opposition leader Mir Hossein Mousavi. It was the worst bloodshed since the height of the unrest immediately after disputed June presidential election.
