Both teams found the net in the opening stages of the game but the goals were chalked off as VAR correctly ruled them as offside.
Manchester City came out after the break the better side and got the deserved opener when John Stones bundled in his first goal for City since November 2017 from close range before Fernandinho got the second goal inside 83 minutes.
Guardiola was happy with his side’s display and also dedicated the win to former Manchester City and England midfielder Colin Bell, who passed away on Tuesday.
"It's for Colin Bell and his family. He helped to build something special for this club. It's an incredible victory for us to beat United away and it was for him absolutely,” the Spanish coach said.
"The team is ready and it was an outstanding performance. We dipped a little bit in the second half, we were tired after the game at Stamford Bridge but when the team has this mentality they can do something incredible. It's not the Champions League but four times in a row to reach the final - I'm so impressed.
"I think that was our first goal from a set-piece. Lately, we have been close to scoring on set-pieces and tonight we scored two goals.
"It's about the consistency. We didn't have a proper pre-season and that's why we need a little bit of time but I think we are already there.
"[The final] is not next week, the game will arrive at the final. We will be in the best possible condition. Tottenham are a top team but we won't think about it yet."