The Blues go to City on Saturday night with their opponents having been hammered by PSG in the Champions League in midweek.
But Maresca stressed this morning there's never a good time to face his old club: "No, I don't believe in this kind of thing, probably on the other side. With this club and these players, when they are in a difficult moment, they want to show how good they are. I don't think there is a good moment to play against City.
"I think it's normal. It can happen. What is not normal is the amount of years they won things, won trophies; what is normal in football is to live moments like they are at the moment. For sure, they will be back soon."
On his relationship with City counterpart Pep Guardiola, Maresca continued: "My contact with him, the club, is fantastic. I will always be thankful to Manchester City. The reason why is because they called me back after an Italian club sacked me after two or three months. We have a fantastic relationship in terms of friendship.
"Pep is strong enough in this kind of thing. For sure, like any human being, he needs support in this moment."
Maresca, meanwhile, admits Chelsea's away form can offer them confidence going into the clash.
He continued: "It probably shows how balanced we are. Everyone is talking we get more points away than at home. I don't think the difference is big. Hopefully in the future we can get more points at home - this is the target. But overall, I think it's something good because of the balance.
"I think if you see the top six in this moment, we beat Bournemouth away, we beat Newcastle at home, we drew with Arsenal and lost to City and Liverpool. It is a matter of balance. We are going to beat the big teams, for sure, but winning tomorrow doesn't mean we will challenge for the title."
Quizzed about new additions, Maresca also stated: "With the club, the sporting directors, we pay attention if something can happen. We will see in the next 10 days if something will happen."
On rumours of interest from abroad in Joao Felix, the manager said: "I said, for sure, Joao is a Chelsea player. The problem for Joao and Christo (Nkunku) is the manager plays most of the games with one attacking midfielder, that is Cole Palmer. They struggle to get minutes, not for any different reasons. They are both top players."
Asked about Manchester United winger Alejandro Garnacho, he said: "I'm happy with what we have in this moment. On the right side it is Pedro (Neto) and Noni (Madueke), on the left we have Jadon (Sancho). We had Misha (Mudryk) but he is not with us. Tyrique (George) is an option."
Maresca concluded by reaffirming his confidence in goalkeeper Robert Sanchez after recent errors.
"Robert is okay. It is a matter for me to understand that anything can happen. How many times has Moi (Caicedo) missed a pass? Many times. How many times has Nico (Jackson) missed a goal? Many times. How many times has Noni missed a cross? Many times. Robert has made four mistakes, it's normal. There isn't any strange thing behind this. It is our job."