Roberto Mancini joined in the Wembley celebrations then warned his jubilant City players not to forget that they have won nothing yet.
Man of the match Yaya Toure's superb second-half goal swept aside Manchester United and fired the Blues into their first FA Cup Final for 30 years.
But manager Mancini, now 90 minutes away from ending City's long wait for silverware, is determined the players should not get carried away with their deserved derby success.
He said: "I am very happy for our supporters, because they deserve what they have got today. It's important for us, but we must not forget that there is another game. We have only won a semi-final.
"We have beaten United, but the Final will probably be harder than this. It's very important for us to win the first trophy. If we win the FA Cup then probably next year we can play for the title.
I want to win this cup for the club, the supporters and all the people who work for Manchester City
The Reds started favourites in the absence of City captain and top scorer Carlos Tevez, but City's mean defence stood firm and finished against ten men when Paul Scholes was shown the red card.
Mancini said: "It's difficult against United, they are some team and they are used to playing these games every year. For us, it was the first time in a long time.
"United played very well in the first 25 minutes and had two chances to score, but after that we deserved to win. In the last 15 minutes of the first half we started to play well and continued that in the second half."
City's boss also believes the semi-final win can be a springboard for Champions League football next season, with Tottenham winding up for a late challenge.
He said: "We have everything in our hands. If we play with the same spirit as today, we will have fourth place. Yaya is a fantastic player, but all the players played a fantastic game today."