The arrival of Edin Dzeko from Wolfsburg has increased competition in attack at City.
"When Mario played for Inter they also had Diego Milito, Samuel Eto'o and Goran Pandev," argued Mancini.
"If you want to win you must have good strikers, especially when you play every three days, as we are going to be doing.
"At the moment I only have Carlos, Edin and Jo. This is a problem."