Mendenhall has been the Steelers' leading rusher in the previous three seasons but has played in just four games this campaign because of injuries.
According to local media reports, Mendenhall failed to show up to Sunday's game against San Diego after coaches told him he would not be active for it, leading to his suspension.
The Steelers (7-6), who are fighting to make the playoffs and face Dallas this week, signed Baron Batch from the practice squad to replace Mendenhall on the roster.
Mendenhall missed the season's first three games with a knee injury. He was also sidelined because of an Achilles ailment and recently demoted to third-string running back.
He has just 113 rushing yards this season. (Writing by Jahmal Corner in Los Angeles; Editing by Peter Rutherford)
