"It was a deserved win for Getafe," admitted the Portuguese. "My players told me the second goal was a handball by Colunga but I don't care.
"Getafe's win was deserved but it was nothing from another world. Real Madrid were bad.
"It was an unacceptable game and, from what I had been analysing, I was not surprised. We totally deserved the defeat."
Mourinho continued to express his disappointment at his players' performance against Getafe in the Madrid derby.
"It was a horrible game," he said. "I have not discussed anything with the players - they have no feedback about what I think.
"I do not want to speak with them. The only conclusion that I want is that they realise that it was more a deserved defeat for Real Madrid than a deserved win for Getafe."
Madrid are now five points behind Barcelona, who won 2-1 against Osasuna away from home on Sunday.