Aguero scored City's winner in their 2-1 Wembley triumph.
But his second-half challenge on Luiz left a sour taste as he jumped on the Chelsea defender's back.
And whilst Luiz did not condemn Aguero, he did claim if the striker had done something wrong, he should be big enough to admit it.
"Aguero's a great player," said Luiz. "He needs to be honest with himself and say I don't like to do bad tackles.
"People are happy when Aguero scores goals and does good things in the game.
"Many kids see the game, watch the game and they want to see good things and not bad things.
"I didn't see it because I was on my back but I felt it a little bit.
"Sometimes in a game people have five seconds when they are angry and do things they don't like to do. I think it was that. I never saw Aguero do a bad tackle on other players. It was five seconds of anger and I forgive him."
The FA said Aguero will face no action for the challenge.
It follows confirmation that referee Chris Foy had at least seen part of the incident and acted on it during the match - Chelsea were awarded a free-kick.