Mortazavi was also suspended from public office for five years, the pro-government newspaper Iran said.
The notorious former prosecutor was suspended in August 2010 over the deaths of Mohammad Kamrani, Amir Javadifar and Mohsen Ruholamini in Kahrizak jail the previous summer.
The men had been jailed in connection with anti-government protests that swept Iran following the disputed June 2009 re-election of hardline president Mahmud Ahmadinejad.
Their deaths, from injuries inflicted in custody, were denounced by lawmakers at the time as a "crime".
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Kahrizak, a detention centre for dangerous convicts south of Tehran, was shut down in July 2009 on the orders of Iran's supreme leader, Ayatollah Ali Khamenei.
Iran's Ebtekar newspaper reported Sunday that Mortazavi's lawyer had not been notified of the ruling taken the previous day by the supreme court.
Mortazavi had announced on Thursday that he would contest the decision, according to the Tasnim news agency.
During his six years as Tehran prosecutor and before that as a judge, Mortazavi was responsible for shutting down dozens of reformist publications and jailing journalists.
Ahmadinejad's re-election, which the opposition rejected as massively rigged, was met with street protests which sparked clashes with security forces in which dozens of people were killed.