"We can talk about Messi and Cristiano Ronaldo, but they are nothing like Ibrahimovic," Leonardo is quoted as saying by L'Equipe.
"At almost 100 kilos and 1.96 metres, he's the best targetman in the world.
"When we signed Thiago Silva and Zlatan this summer, everybody was really impressed with what we had done. In two or three years' time, people will react completely different."
PSG, who have yet to win a Ligue 1 game this season after drawing their first two matches, host Bordeaux on Sunday.