The City youngsters put in a dominant derby display with goals from Sam Edozie, and a brace from Cole Palmer proving the difference at the Academy Stadium.
After the game the City boss praised the effort his side put in on the night to overcome our local rivals.
"They give everything," he said. "When they dropped they then work hard."
Maresca added that his team's work ethic is something that hasn't just appeared in the victory over United, but has been a common theme throughout the 2020/21 season.
"They deserve this moment." He said.
"It is never easy to create the right enviroment when sometimes you have players with the first team but they give everything.
"The guys that have been with us everyday have been fantastic, so it's been very good."
A dominant team performance saw City control the game throughout, and whilst there were some special individual moments - notably from Cole Palmer - Maresca believed the victory was a real collective effort.
"I think all of them played very well," he said.
"I think in terms of thinking about the whole team we worked well. In the end we deserved to win and we are happy."
A key component to City's recent, impressive run has been our free-scoring form.
However, the EDS boss believes his team's solid defensive display is just as important as the goals at the other end.
"The clean sheet is very important," he said.
"When you want to try to win games and competitions you have to be solid at the back, and tonight we showed we were solid."
Victory over United now means City can be crowned Premier League 2 champions if both Blackburn Rovers and Tottenham Hotspur drop points this gameweek.
However, the City boss revealed his side will be ready for whatever outcome they face with just three games left to play.
"We are going to enjoy tonight's game and then on Monday night we will see what happens there," he said.
"If not at least in the worst case there is three games to go with eight points the difference so I think tonight was very important to win the game."
The EDS return to action away at West Ham United on Friday 23 April at 16:00, and you can watch the game live on City+.
It will allow you to watch full match replays of all men’s and women’s matches 24 hours after the final whistle and original CityTV productions.
You can sign up to a 30-day free trial, after which CITY+ is just £1.99GBP / month.