The Italian tactician was speaking in the aftermath of his side's impressive 2-1 win at Old Trafford on Monday evening, where goals from James Milner and Sergio Aguero, either side of a Vincent Kompany own goal secured all three points for the Citizens.
It's a result that closes the gap between themselves and United at the top of the table to 12 points with seven games remaining, but Mancini is adamant that their title challenge is over.
"The championship is finished but we deserved to win because we played better, we played good football," Mancini told the Daily Telegraph. "We didn't take any risk.
"We know that we can win the title next year. This year we did some mistakes but we can do nothing now. The season is gone.
"It is important we continue to win because we have another seven games but it does not change anything for the future.
"We need to continue to play like this for next season. We have two or three months where we can work well, where we can improve our team. I think we showed here we can't be 15 points behind."
In the build-up to last night's game, Mancini stoked the derby flames by claiming that Manchester United didn't deserve to be 15 points clear at the Premier League summit, intimating that some clubs had showed Sir Alex Ferguson's side too much respect.
And, he will have frustrated Red Devils fans even further after overseeing Manchester City's first back-to-back victories at Old Trafford in 41 years, as well as laying down a psychological marker for the 2013/14 campaign.
"This is important for us because we can get second position," Mancini added. "Maybe we have one game in hand and if we win the game against Wigan we go 10 points in front. After that maybe we don't have a problem.
"This is for our supporters because they deserve this victory. After being 15 points behind it was important for them."