"Barcelona and Real Madrid every year buy two or three players and spend a lot of money," Mancini told BBC Sport on Tuesday.
"I think for Manchester City it will be the same. We need to improve. We need to have the strength to play Champions League and Premier League.
"For this we need to have a good team, a strong team with a good mentality, but I'm sure we will do it."
Real Madrid and Barcelona have spent an estimated total of ?105m ($170m) each, over the last two seasons, to recruit players.
City now have the spending power to match the Spanish giants and, as Mancini plans his quest for European glory, he is pleased with how his side have dealt with the pressures of the Premier League this season.
He said City -- top-flight champions for the first time since 1968 -- were worthy winners of the title because, unlike second-placed city rivals Manchester United, they were never beaten heavily by anyone.
"We lost 1-0, 1-0, 1-0 -- always games we could win," he said. "Manchester United lost 3-0 to Newcastle and 6-1 against us, but we never had a game like this.
"We worked very hard. We deserved to win this."
Mancini, 47, added that his relationship with strikers Carlos Tevez and Mario Balotelli remained good.
"It's not difficult to manage Tevez," he said of the Argentinian who refused to play for City for six months after refusing to come off the bench during a Champions League game at Bayern Munich in September.
"He's a good guy. We had a good relationship always. I don't know why we had that situation in September but in the end he's a good guy and a fantastic player."
Balotelli received two red cards during the season, and Mancini had words of caution for his compatriot.
"Mario is different, he's young, but an incredible talent," Mancini said.
"He's young, and for this reason sometimes he can have bad behaviour -- it's normal. But it's important for him to understand he can lose his talent.
"He can play football for another 10 or 12 years. I hope that now, after this title, he can understand that it's better that he starts to work in a good way."