The Italian has already seen England international Elliot Anderson arrive from Nottingham Forest, highly rated winger Jeremy Monga join from Leicester City and academy graduate Pierce Charles return from a loan spell at Sheffield Wednesday, while long-serving figures Bernardo Silva, John Stones and Nathan Ake have all departed the Etihad Stadium - Silva joining Real Madrid, Stones leaving for Inter, and Ake completing a reported £7m move to Fenerbahçe.
With the Community Shield against Arsenal less than a fortnight away and a Premier League opener at home to Bournemouth the following weekend, Maresca used a press conference ahead of Wednesday's friendly with K-League All Stars to address his squad's remaining needs.
"Fortunately this is a squad that doesn't need to do many things," he said. "At the same time, we already know the squad lost some important players with experience with Bernardo, John, Nathan…different players. For sure, there are things we need to do.
"Hugo [Viana, sporting director] is here. Also Ferran [Soriano, CEO] is here. We just try to speak day by day to see if we need to do something. For sure there are things we need to do. We are in communication every day. The reason I said there are things to do is because the transfer window is open and when it is open, anything can happen.
"It is August and then from September, when it's closed, it is completely different."
Manchester City face the K-League All Stars, an assembled squad representing South Korea's top flight, at Seoul World Cup Stadium at midday UK time on Wednesday. Maresca confirmed young forward Ryan McAidoo, who impressed in City's 1-1 draw with Inter Milan earlier on the tour, will miss the game with a shoulder problem.
"We have many young players with us, and in the last game against Inter some of them played some minutes," he said. "Ryan McAidoo was good but even the rest. Unfortunately, McAidoo will be out tomorrow because he has a small problem with his shoulder - nothing important. Always City's Academy has good players, it is exciting because of that."
On his broader progress since taking charge just over a month ago, Maresca added: "General concept - defensively and offensively. The way we want to defend and attack with some patterns. It's a different idea we started to work on since I joined the club. For sure, we want to try to win games, that is the main thing but at the same moment we want to see the team improving day after day."