Fulham had the lead through Andreas Pereira before City fought back through Mateo Kovacic (2) and Jeremy Doku. Rodrigo Muniz scored a second two minutes before fulltime for the visitors.
Guardiola said: "It was intense, it was tight, chances for them, chances for us. We started well and created many chances and it was tougher when they went to five at the back. It was a risk to manage it but in the end we did.
"The two with Kovacic were good when they had five at the back because only the striker can defend him in that situation and that makes the transitions less dangerous. We used that weapon and Kova did really well.
On Jeremy Doku's winning goal, he said: "It was really, really good. We always talk about his ability to dribble but it is then about the final pass, that last action. I was diagonal to him and the ball made an incredible curve effect. Really happy for him. The last game against Bratislava he was really good and today as well."
"We have always had the ability to do it. Like Brentford, the rest of the game we were playing really well but sometimes it happens.
"The first goal with the pass from Jimenez was not expected by anyone so you have to give the credit to the opponent. They had more good chances too but Ederson made some incredible saves."