City, who had led the Barclays Premier League since October, now trail Manchester United by four points at the top after being overhauled by their rivals this month.
Yet with a game in hand against Chelsea on Wednesday - when Carlos Tevez could make his much-publicised return - and a derby clash with United on April 30, Mancini has not lost any confidence.
The Italian said: "We will win the title, we will win. We will do everything to win the title. We need to think positive, always.
"Until now we have had a fantastic Premier League, we need to continue like this.
"It is better to stay on the top - always - but I said a month ago it could be that we will go into the second position. This can happen.
"We had difficult fixtures, different from United, but it has not changed. We have everything in our hands.
"There is one game difference - potentially we are one point behind.
"Maybe if we win the next two games we go two points up. We need to go our way, we can't think about United."
City lost top spot as they were beaten at Swansea nine days ago, a result which was followed by elimination from the Europa League at the hands of Sporting Lisbon.
Mancini does not think his team are cracking under pressure.
He said: "No, I don't think this. We know United are used to staying there, always, but this is the only difference between us and United in this moment."
Nevertheless, City could be given a lift by the return of Tevez, who is set to be named on the bench for Chelsea's visit to the Etihad Stadium.
The 28-year-old has not played for six months, but has now been back in training for five weeks following the closure of his dispute with the club.
Mancini thinks it could be next month before the Argentinian, top scorer in the past two seasons, is fit enough to start again, but he is now ready for action.
Mancini said: "He is getting better but I don't think Carlo can have more than 25-30 minutes.
"A player like Carlo needs to play but for 90 minutes but, at this moment, it is impossible.
"If he can play 30 minutes, after that 45 in three or four games, then he could have 90 minutes, easily."
Although Tevez could provide an extra cutting edge up front, City still have problems at the opposite end of the field with first-choice central defenders Vincent Kompany and Joleon Lescott injured.
With Lescott already ruled out with his groin injury and Kompany struggling to overcome his calf strain in time, Stefan Savic and Kolo Toure could continue at the back.
They might have to deal with a fired-up Fernando Torres, who finally ended a long barren run with a double in Chelsea's FA Cup win over Leicester on Sunday.
Mancini said: "I am happy for Torres, I like him as a guy and a player. He scored again because he deserved this.
"I don't know what will happen tomorrow [Wednesday] but I am happy for him.
"But we know tomorrow we play not against Fernando, but against Chelsea. Chelsea are a top team."
Chelsea appear to have put aside some of the problems which led to the recent departure of manager Andre Villas-Boas with a four-match winning run under Roberto di Matteo.
That sequence included a memorable Champions League fightback against Napoli, but Mancini always felt that was within their capabilities.
He said: "I am happy to meet Di Matteo, he is a good manager, he did very well at West Brom.
"Now he is continuing to do very well with Chelsea, but tomorrow I hope we can win.
"Chelsea are a good team but they were before with Villas-Boas."
After a blistering start to the season, City lost their first league match at Stamford Bridge in December.
Mancini still believes his side deserved to win and would not mind seeing roles reversed tomorrow.
He said: "We were really unlucky because we dominated the game for the first 30 minutes.
"I hope in the last 10 games we should play sometimes and be lucky - maybe we will win when we don't deserve to win."