The 34-year-old scored a superb free-kick in City's 2-1 win over Bournemouth on Wednesday.
Silva will leave Manchester at the end of this season, and Guardiola says he will be in peak condition for his new club.
"He is in an incredible performance, he is one of the guys who came back from lockdown in an incredible position," Guardiola told Sky Sports.
"He's in an incredible condition right now, incredible condition, and the way he is playing is really good.
"His mentality with and without the ball, scoring goals – it's his second in a row with the free-kick. He's really, really well."
Guardiola continued: "All the people think about it with this situation, to come here and play in this league it will not be easy, but it shows the mentality of David, he has [it], so the reality was like this.
"He decided to go, so hopefully he can find the place where he wants to play his last years."