The Argentine will not be risked at Villa Park after picking up a knock against Manchester United but should be fit to face Bayern Munich in the Champions League on Wednesday.
The Argentine international scored twice in Sunday's 4-1 thrashing of neighbor Manchester United at the Etihad Stadium but picked up an injury during the game. While Pellegrini expects the striker to be fit in time for Wednesday's Champions League game against Bayern Munich, he confirmed that his star will not be risked at Villa Park.
"Aguero finished the last derby in the last play with a small pain. I think it was nothing important, but I think it was a risk for him to play three games in the same week," Pellegrini told reporters. "We will leave him for next Wednesday, but he will be absolutely fine."
David Silva is also expected to miss out once again as he recovers from a thigh problem, with Pellegrini explaining that he has an outside chance of playing on Wednesday, adding only: "We will see in the week."
The City boss insists that his team will not be distracted by the upcoming clash against the European champion and will need to play well to beat Paul Lambert's side.
"I am sure nobody is thinking about Bayern Munich. We are all thinking about Aston Villa," Pellegrini said. "We know it is a strong team playing at home. We need to play a very good game if we want to win and we need to win away now."