Guardiola said, "We can now talk about the Treble. Of course we still have to win the Champions League. We performed so well for our city and our fans.
"They follow man to man so tight and we didn't expect them to defend so narrow. We found more spaces in the second half.
"Tomorrow and the next day they can have off. We've then got three or four sessions to train for Inter Milan. We'll travel on Thursday morning after training.
"It was so important for us today. The FA Cup is so nice.
"I'm a Barcelona fan but I will love this club for the rest of my life. I know today we gave our fans a good gift to enjoy against our neighbours."
On Gundogan, he said: "What a season he has had. The skills are there but he also had the mentality. He plays the big games like they are friendlies, he can cope with the pressure."
And on Stones, Guardiola added: "Incredible player. He's played so well lately and has given the opportunity to play in this certain way. All of the guys were amazing.
"Stones has the quality to pass the ball and he can arrive into the attacking positions to control the play."