City finished with a flourish as they impressively beat Bayern Munich 2-0 at the Etihad Stadium, but they remained third in Group A as Napoli beat Villarreal in Spain. The results mean the Barclays Premier League leaders will drop into the Europa League, but Mancini could not fault the effort of his players.
Mancini said: "We are disappointed because we wanted to go through in the Champions League. I am personally very sorry for the club, our supporters and my players. I think they deserve to play in the Champions League but that is it, we can do nothing now."
He added: "Usually with 10 points, teams always go through - or 99%. But in this group it was not enough. I think Napoli got one point more than us and they deserved to go through."
City's slim hopes of progress were still alive with 65 minutes gone as they led through David Silva and Yaya Toure while Napoli were still being held.
That changed as Napoli then scored twice and the closing stages were played out in a subdued atmosphere.
Mancini vowed to lift the gloom and launch a concerted effort to win the Europa League as consolation.
The Italian said: "For Manchester City it is an important trophy.
"We need to win more trophies, if possible.
"I can understand at this moment thinking it is not - it is not the Champions League. But for us it will be important if we can get to the final. For Manchester City that would be good."
Source: PA
Source: PA