Sterling tripped when through on goal during City's rampant 6-0 win over the Ukrainian champions, having kicked the turf when shaping to shoot.
Referee Viktor Kassai incorrectly ruled that the England winger had been felled by Mykola Matvyenko, however, awarding a penalty that Gabriel Jesus converted.
Sterling subsequently apologised for not informing the referee of his mistake, although Guardiola insisted that the City forward, who has signed a contract extension until 2023, was right not to do so.
And, ahead of Sunday's Manchester derby, Guardiola has again come to the 23-year-old's defence.
"I think this time I realised it's unfair because I don't know why you should criticise Raheem," Guardiola told a news conference.
"It's not diving either. Tripping is a mistake, it was a bad decision of the referee.
"He's an incredible guy, he does absolutely everything on the pitch, fighting in front and he made a mistake because he's 23 years old.
"He maybe goes too fast, maybe he has to do it slower. Believe me, what the people said about this action I didn't understand.
"He will become stronger, he's stronger than when we met each other in the first year. Now, he controls these emotions much, much better."