With Gabriel Jesus sidelined due to a foot injury, Aguero is set to get his chance at the Etihad Stadium on Tuesday.
The Argentina international had battled to win a place, leading to speculation over his future in Manchester.
Guardiola said it is up to the 28-year-old to deliver and add to his 18 goals in all competitions this season.
"With the guys who score goals, it is talent, it is instinct, how they have to move, create spaces," the Spaniard said.
"It is not to be controlled. He is going to have to do it himself. Sergio has enough experience. He knows, everybody knows.
"I know what he is trying to do, without the ball and with it. We are going to talk to him, like with all of his team-mates, to convince him in these two games."
Guardiola is eager for European success, although City come up against a team sitting top of Ligue 1 and having scored 76 goals in 26 league games.
"It is one of the most beautiful competitions to play, maybe not the most important, but the most beautiful and we have to do our best," he said.