According to the report, Hernandez was believed to be involved in a gang-related brawl after he agreed to be the lookout for one inmate who went into another prisoner's cell at the Souza-Baranowski Correctional Center in Lancaster, Mass.
Hernandez was put in a special management section and the three men involved in the altercation, including Hernandez, are expected to be disciplined.
A Massachusetts Department of Correction spokesman declined to comment to CNN when asked about the report.
Hernandez, 25, was convicted last month of the June 2013 killing of semi-pro football player Odin Lloyd, who was dating his fiancée’s sister and was sentenced to life in prison without the possibility of parole. He is appealing the conviction.
Hernandez also attacked an inmate last year while he was awaiting the trial for Lloyd’s murder at the Bristol County, Mass., jail.
Hernandez is due in court later this year to face murder charges in the deaths of Daniel de Abreu and Safiro Furtado, who authorities say was killed after a nightclub confrontation with Hernandez in 2012. He has pleaded not guilty to the charges.