Atletico Madrid striker Aguero is set to join City today.
Asked if he is a replacement for Tevez, Mancini told AFP: "No. I hoped to recruit an extra attacker long ago already. The case of Carlos Tevez is still pending. Carlos said he wanted to leave, but nothing is done.
"If his case is not resolved before the start of next week, I'll rely on him for the Community Shield against Manchester United."