Italian is also convinced Kolarov and Balotelli will be successes...
Mancini, 45, oversaw another summer of massive spending as he brought in James Milner, David Silva, Yaya Toure, Mario Balotelli, Jerome Boateng and Aleksandar Kolarov. Results have so far yet to match their spending, with just one win recorded in the Premier League this season.
Speaking to Il Messaggero, he asked supporters to keep faith that they'll eventually be on a level peg with Manchester United and Chelsea.
He said: "Our objective is overcome Chelsea and Manchester United but to accommodate everyone. It will take a little time - even last Saturday we wasted a number of incredible opportunities to score.
"We have to chase but, eventually, City will be one of the main clubs."
The Italian also asked for time to allow injured stars Kolarov and Balotelli to prove their worth.
"We focus strongly on young, value players," he continued.
"Kolarov and Balotelli will do well in the Premier League. Unfortunately, both are injured and this has hampered our start of the season.
"Mario is certainly a factor that can make the difference. He is an extraordinary talent who has everything to become a number one - even in Italy's national team."