Real had won their last seven league meetings against Getafe and appeared set for another triumph when Gonzalo Higuain put them ahead in the 27th minute.
"Getafe deserved to win. The players say there was a handball by Colunga, but I don't care.
"They didn't play fantastically, but they deserved to win and I congratulate them. We played badly and our performance was unacceptable. I'm not frustrated, because the final result, in terms of the match, isn't a surprise," said Mourinho.
Mourinho played down the importance of Real Madrid not having won in any of its three official matches.
"I don't think it's ever happened to me. But each season new things happen: I'd never won 100 points, or scored 120 goals. My career is getting longer and this is Real Madrid and it's not normal that from six points available you only win one. The Supercopa is different because it's a knock-out competition. Today has been a horrible match".