The Swede is currently back at the San Siro with Milan after an impressive two years at Major League Soccer outfit LA Galaxy, where he bagged 53 goals in 58 games.
Mancini feels Ibrahimovic will be remembered as one of the greatest forwards to play the game once he hangs up his boots.
"I put him on the same level as Messi and Cristiano Ronaldo. He won the league title wherever he went, scoring a ton of goals.
"He's done well at Milan too this season, but I don't know what his plans are for the future."
Mancini also shared his view on his former club Inter Milan, who with he won three league titles, making a push for Barcelona icon Messi.
"I think that if [Massimo] Moratti was still the President of Inter, he would've certainly tried to sign Messi at this moment," Mancini noted.
"After all, he brought Ronaldo to Inter, at the time one of the best strikers in the world."