Moises Caicedo struck to cancel out United's opener scored by Bruno Fernandes.
Maresca said afterwards: "We knew that it was a difficult game for different reasons. For a big part of the game we were in control, there was a desire to win the game and we lost our balance in the last 10 minutes or so.
"Overall United were similar, we expected them to be a bit more aggressive. Overall the game was clear.
“When you go down in this stadium it’s very difficult to come back but we did that. Then we tried to win it.
"Moises Caicedo has been fantastic since I came to the club. They showed me the foul on Cole Palmer, there is no intention to take the ball and it is dangerous."
Maresca insisted Lisandro Martinez should've been sent off for his challenge on Palmer.
"I think it is quite clear for all of us but the referee took a different decision," said Maresca.
"When you don’t go for the ball and just the man it is a red."