Manchester City’s top goalscorer Aguero only featured on the bench in the Champions League clash against Barcelona at Camp Nou before he was forced to watch on as his side fell to a 4-0 defeat at the home of the La Liga giants.
It has also been suggested that Aguero could be allowed to leave City at the end of the season but Guardiola has dismissed reports that the Argentine could be sold.
Guardiola told reporters: “It was a tactical decision. I wanted one more midfielder, I tried to keep the ball in the Camp Nou and when you have the ball, Lionel Messi, Neymar and Luis Suarez don’t.
“I spoke with Sergio and he was understanding, I thought in the last 30 minutes, with the Barcelona centre-halves tiring, he could help a lot from the bench.
“When Sergio decides to leave it will be his decision. Next time before you (the media) decide he is not in my plans you can call me.”
Aguero has scored 11 times in all competitions this season but he is without a goal in his last four outings.