Forest affirmed their top four credentials thanks to Callum Hudson-Odoi's 83rd minute winner.
Speaking after the 1-0 City Ground triumph, Nuno said: "The organisation, the resilience, we know how hard it is to play City. We tried to give them nothing but it is always difficult."
On Morgan Gibbs-White's pass for Hudson-Odoi's winner, Nuno said: "When Morgan drops a little bit deeper he has the ability to do that but it is all about Callum. But it is not about individuals, all the boys work very hard.
"We have shown a big improvement from last season but now is about enjoying the moment. We are in a good place, but the fans are happy and we keep going on this journey.
"The fans are everything. The City Ground has been beautiful for us. There is a bond, a trust. They are behind us and Callum's goal is part of them also."
Nuno continued: "It was a tough game everybody saw how good Manchester City are, they had us on the ropes but the boys worked very hard. Of course they were going to have chances but then it was then about us taking ours.
"It was good today. It started with Anthony (Elanga) and Chris (Wood) trying to cut the lines to give time to the back lines but definitely a very good defensive display. We tried to block and then break through the middle with Anthony.
"The focus does not change. We are on to the next one, Ipswich. It shows the progress of the squad but there is so much football to be played. Let’s focus on the journey and move on to the next one."