Nicolas Jackson scored in both halves at Villa Park, with Erling Haaland briefly equalising for City after the interval before the Aston Villa striker struck again to secure a 2-1 home victory.
The result ended Manchester City's perfect start to the Premier League season, leaving Maresca to reflect on a performance in which he felt his team had done enough to take something from the game.
“Performance overall was good. Amount of chances we created. Second half we only conceded the transition of the goal.
“Sometimes you have to defend a bit better or be a bit more lucky in that transition but it's football. We learn from that and move on.”
Maresca was particularly frustrated by the circumstances surrounding Villa's two goals. Jackson opened the scoring in the sixth minute after Marc Guéhi lost possession, with John McGinn setting up the finish. Haaland levelled in the 52nd minute, heading in Iliman Ndiaye's delivery, but Jackson restored Villa's lead eight minutes later from Ibrahim Mbaye's low cross.
Asked whether both goals could have been avoided, Maresca replied:
“Absolutely, both. Sometimes you have to be a bit more lucky because we only conceded those two chances. But we created a lot of chances.
“We had many chances. We played most of the game in their box but you have to be clinical and avoid mistakes like the two goals we conceded.”
City enjoyed the greater share of possession but could not turn that control into enough goals. Villa goalkeeper Zion Suzuki made several important saves as Unai Emery's side protected their advantage, while the visitors were left to contemplate their first league defeat of the campaign.
The result also continued City's difficult run at Villa Park, where they have now lost on successive visits. Maresca was unwilling to look beyond the performance itself, however, insisting his focus was on what his side could learn.
“We will try again next season. I can only analyse today and I don't think we deserved to lose today - but we lost.
“You can always learn something. For sure there are things we can do better today.”
City must now recover and prepare for Brighton, with Maresca expecting another demanding assignment rather than allowing the defeat to dominate their preparations.
“We will see. It will be a different game, they are doing a fantastic job. It will be tough in both games. But we must recover and prepare for that.”
For Maresca, the immediate challenge is to turn the disappointment into a response. City created opportunities to leave Birmingham with a result, but their errors at either end of the second half ultimately proved costly.