Six people arrested during the riots on Ashura Day were sentenced to death,
Tehran Prosecutor Abbas Jafari Dovlatabadi was quoted as saying by the Fars news agency.
He added that the condemned are appealing the court's decision. After the Appeals Court issues its verdict, a final decision will be made.
Dovlatabadi said the decision regarding the 250 people arrested after Ashura Day was issued quickly. However, another 100 prisoners are waiting for their verdicts or sentencing.
Earlier it was reported before that the Tehran Revolutionary Court sentenced 11 people to death who participated in the riots on Ashura Day, which resulted in a clash between the police and opposition forces.
Two of the condemned, Mohammed Reza Ali Zamani and Arash Rahmanipur, were executed.
Opposition supporters and police clashed on Ashura Day Dec. 27 in Tehran. Eight people died, including seven men and one woman.
According to international news agencies, 15 people died and over 550 were arrested.