The Lord of the Rings actor stated that the Blancos coach would not have picked on somebody like Diego Simeone, and also criticised his preferred style of football
The 53-year-old star, who lived in Argentina for several years during his childhood, recently revealed that he is a Madrid fan.
But his affection for the Spanish giants does not appear to extend to their Portuguese head coach.
"I like football to be played on the floor, colourfully, enthusiastically and artistically, and Mourinho does not seem to be a fan of that kind of game, so I have a different approach from him as a fan," the American actor told Sportyou.
Mortensen also criticised the former Inter coach's behaviour during last season's Supercopa match with Barcelona, when he famously poked Barcelona's Tito Vilanova in the eye during a touchline brawl.
"It is little comfort to me that Mourinho's behaviour goes against the tradition of Real Madrid," he added.
"I would like him to be educated, not going to the locker room while playing to spite others, and not sticking his finger in peoples' eyes.
"It is cowardly to make that offensive gesture towards Tito Vilanova, a polite guy, and not towards Simeone, who would have kicked his a**e."
Mortensen, however, did add that he hoped Mourinho would "win us the 10th [Champions League] this year."