Ayatollah Ahmad Jannati says in a Friday prayer sermon that the clerical leadership's opponents must be killed "for the sake of God" and that Islam permits rulers to execute "hypocrites."
He also praises the hanging on Thursday of two men who were accused of belonging to armed groups aiming to topple the ruling system.
Nine other people arrested in the heavy crackdown against opposition protests have been sentenced to death, according to officials. Massive protests erupted after disputed presidential elections on June 12, and hundreds have been arrested.