Pantilimon was part of the City side that lost 3-2 to United on Sunday at the Etihad Stadium but he believes it hasn't knocked the team's spirit.
The 24-year-old also complained that the dismissal of Vincent Kompany in the first half was a key factor in the defeat.
Pantilimon said: "We are happy - we agreed with the fans - because the referee made it like this by expelling a player really early. I don't think that was great.
"It has not damaged our confidence. It was an interesting game, but losing a player after ten minutes is not normal. It was a foul but a normal foul and not a direct red card."
The Romanian will be aiming to play against Liverpool in the Carling Cup semi-final first leg on Wednesday despite Joe Hart being expected to return for Roberto Mancini's side.