The Citizens crashed out of the Champions League on Wednesday, despite beating Bayern Munich 2-0 at the Etihad Stadium, after Napoli saw off Villarreal by the same scoreline in Spain.
But Mancini remains defiant in the wake of the group stage exit, believing his team can secure Europa League glory after dropping into the competition.
City currently hold a five-point lead at the summit of the Premier League and have a League Cup semi-final with Liverpool to look forward to next month.
“We are disappointed, that is normal. We wanted to go into the second stage and now we can do nothing,” the Italian said.
“It is my opinion next year, that if we play Champions League, we will do better.
“I am sure we will improve, but it is important to finish well this year. When I say finish well this year, I mean to maybe win two trophies.”
Despite claiming a credible 10 points - a tally that would have been enough to qualify for the knockout stages in previous seasons - it proved not enough to usurp either Bayern and Napoli, with all three sides doing the double over Villarreal.
However, Mancini believes the experience they have gained will prove fundamental if they are to reach the last 16 of the Champions League next season.
“In the Champions League you know that every game is difficult," he added.
“If you meet a team that is maybe not as strong as you, and if you don't play those games 100 percent, you concede goals.
“We can improve on this. I think we did well and I also think we were unlucky because in Naples we didn't deserve to lose.
“But this is football. You can play well but if you concede two goals you have to take more risks. In the Champions League you can't concede many goals, you must pay attention every game.
“You should arrive at the last game and it should depend on you - if you win you go through. We arrived in the last game depending on Naples and this is difficult.”
