Ferguson's side, who entertain struggling Aston Villa on Sunday, saw their lead at the top of the table cut to five points with five games remaining after a shock midweek defeat at Wigan.
Second placed City can move within two points of their title rivals if they beat Norwich at Carrow Road on Saturday.
Yet Mancini, speaking after his side's win over West Bromwich Albion on Wednesday, conceded that the title race was over and that United had 'fantastic spirit'.
Ferguson clearly believes Mancini's comments are meant to take the pressure off his players and heap it on United.
The Scot laughed off Mancini's claims and insisted the race for the Premier League is still very much alive.
"I think he maybe picked the wrong time to say it. There's five games still to go," Ferguson said on Friday.
"The twists and turns of the Premier League are fascinating and we had to experience that last season when we played Chelsea in the third or fourth final game, a vital game for us, and we won.
"The experience helped us that day and hopefully it does again.
"The Sunday game is the one to focus on. The rest takes care of itself really. After Sunday's game, which we'll hopefully win, there's four games left.
"You eventually whittle all the games away and you're left with none and hopefully we'll achieve what we want to achieve."
United's defeat at relegation-threatened Wigan ended a run of eight straight top-flight victories, and Ferguson is demanding his side bounce back in style when Villa visit Old Trafford.
Villa, managed by Alex McLeish, are 15th in the table -- six points above the relegation zone with six games remaining -- after a run of one win in 10 league games.
"Obviously the disappointment of losing that (Wigan) game makes it important we get back on track on Sunday," added Ferguson, who could recall Paul Scholes and Nani to his starting line-up.
"I think they're probably safe (Villa) but you never know.
"They've six games left and they're six points clear, they can't be dead sure.
"As they were against Liverpool and Stoke recently, I expect them to be really determined.
"I think Alex has had a rough first year at the club, not being able to buy players and sold a few players.
"He's had a couple of bad injuries in losing Richard Dunne and Darren Bent. Of course Bent's goals are a big loss.
"But Alex is a very capable manager and I think he's coped with it well."