The Algerian winger was City's top scorer in 2021/22 with 24 goals across all competitions.
However, his volley in the 4-0 victory was his first Premier League strike of this campaign and his second in all competitions after a penalty against FC Copenhagen on Wednesday.
But the manager did suggest the 31-year-old could soon be back to his best.
"He is getting better," said Guardiola.
"He made a magnificent goal. He missed one but scored a great goal. He is getting better.
"Training is good, day in and day out. Be fit and after he will be back."
Click on the above video to hear everything Guardiola had to say...