The 26-year-old Morocco international worked with Redknapp at QPR, but the duo fell out during the 2014-15 season.
Back in October 2014, then Rangers boss Redknapp claimed that Taarabt was overweight and not fit enough to play a competitive game of football.
“I pick people who want to try, who come in every day and work, train and show a good attitude,” The Daily Mail quoted the former West Ham United manager as saying at the time.
“When he starts doing that, if he ever can, maybe he'll get a game. I can't protect people who don't want to run and train, and are about three stone overweight.”
Taarabt, who has joined Portuguese giants Benfica after leaving QPR at the end of the 2014-15 season, has now hit out at Redknapp.
“Harry is not a bad person but he is a very bad coach and, for me, a very bad manager,” the former Lens attacker told The Sun.
It is a strong accusation from Taarabt against a man who is well respected in the footballing community.
Redknapp has been in charge of the likes of West Ham, Southampton, Tottenham and QPR in his career.
The Englishman is without a managerial job at the moment, having stepped down from his role at Rangers midway through last season due to health issues.