The England international gave away the ball cheaply for Villa to take an early lead through matchwinner Nicolas Jackson in the 2-1 loss on Saturday.
City manager Maresca has come to the defence of his centre-back, who has started and completed every Premier League match for the club this season.
"I'm completely, especially in this moment, happy with Marc," said the Italian head coach at the pre-match press conference.
"The way he reacted was fantastic. He is a top guy, a leader, one of the captains and I love Marc to be honest. When they make some mistakes, they recognise. Marc is aware now.
"He's played all minutes since the start of the season with us and the international team. In the last two weeks he didn't play Champions League game, he played 45 minutes the other day so he's completely okay."
Maresca also issued a squad update ahead of hosting Brighton and Hove Albion in their Fourth-Round Carabao Cup fixture at the Etihad Stadium on Wednesday, confirming that goalkeeper Geronimo Rulli will start the match.
"Yes [Rulli will play tomorrow]," added the former Chelsea boss.
"He's good. Before I arrived here, I had a conversation with him, he knows his role and that's important. Day by day he is helping a lot. When he has played, he was good and tomorrow he will play again.
"After Villa, we gave five players three days off. Erling [Haaland], Elliot [Anderson], Gigio [Donnarumma], Ruben [Dias] and Josko [Gvardiol]. Go away on holiday. Three days off, go, come back. Full energy."
Manchester United legend Wayne Rooney believes the club's players must take greater responsibility for their disappointing performances, insisting that manager Michael Carrick is being let down by his squad.
Fleetwood Town produced a remarkable Carabao Cup upset by eliminating reigning Premier League champions Arsenal in a penalty shootout to book their place in the quarter-finals.
Manchester City manager Enzo Maresca has confirmed that Geronimo Rulli will start Wednesday's Carabao Cup fourth-round tie against Brighton, with changes expected as his team face a demanding run of fixtures.
Xabi Alonso has backed goalkeeper Mike Penders to recover from his costly mistake against Tottenham Hotspur, confirming the young Belgian will start Chelsea's Carabao Cup clash with Liverpool at Anfield on Wednesday.
