Laudrup feels that the referee made the wrong decision when he showed the red card to Nani following his high tackle on Alvaro Arbeloa.
The sending off arguably cost United a place in the last eight of the competition as Real fought back strongly with a man advantage and turned the score around to lead 2-1 from being a goal down.
"A yellow card maybe, but a red card? Absolutely not," Laudrup told reporters in a press conference.
"I don't think it matters whether it's a referee in the Premier League, La Liga or a Champions League game.
"It was just a bad decision. Referees are human and make mistakes, there is no problem with that, and sometimes it goes against you."