Mancini saw his side fall to a last-minute Robin van Persie free kick which completed a dismal week for the Etihad faithful as they also crashed out of Europe, finishing bottom of their Champions League group.
| MANCHESTER CITY LATEST
|2/1||Manchester City are 2/1 to win the Premier League with William Hill
"Things aren’t going well but I know we will still have a great year," Mancini told reporters.
"United have more experience but we have a much better team and play much better football. Six points is not a big difference with 24 games still to play.
"We need to try to win five or six games in a row to try and reduce the gap."
The former Inter boss was happy with his side's performance against United on Sunday and urged his players to keep on fighting for the title after winning the league in the last minute of last season.
"Even though we lost on Sunday, we showed that we are a really strong team and can win the title again," he added.
"We were unlucky. We dominated long spells of that game — and did not deserve to lose.
"The Premier League is the best campaign in the world at the moment and as we know from winning last year, you can lose a game in the last second."