Real Madrid centre back Pepe was dismissed during Portugal's ill-fated 4-0 loss to one of the World Cup favourites Germany, after headbutting hat-trick hero Thomas Muller.
The 31-year-old earned his marching orders in the 36th minute, providing his country with no chance of playing their way back into the game having already conceded twice. Muller struck again moments before the break before ruthlessly completing his hat-trick in the second half.
Pepe is now suspended, leaving Portugal in a must-win situation on Sunday, June 22 against a well-oiled USA if they are to salvage their hopes of progressing into the knockout phase.
Commenting to Yahoo, Mourinho said: "I think obviously the second goal is his fault. Nobody contacted him, no challenge and [Mats] Hummels scored the second goal. After that I think the frustration of the mistake comes up, he loses possession with the pressure of Muller and after that we can say is not a real aggression.
"Maybe he doesn't deserve a direct red card but because, in spite of not being a clear aggression, there is a body language that many, many times pushes the referees to have these kind of decisions.
"To leave a team playing with ten men for such a long time is obviously a big handicap for the team."
Born in Maceio, Brazil in 1983, Pepe was called up to represent Dunga's Brazil in 2006 yet rejected the invitation as he wanted to wait to become a Portugal citizen. He made his debut for his naturalised country in 2007, a goal-less draw against Finland. He has since gone on to receive 59 caps and has twice been named as a player in the team of the season (UEFA 2008 and UEFA 2012).
"The fact that is not even a Portuguese man, I think that should put even more pressure on him to behave in a certain way, which he didn't," concluded Mourinho.