The victory was thanks to a goal from Erling Haaland, who has been praised by Guardiola for his performance.
"We played well in the first half, but we couldn't score more goals, which would have made the game easier," said Guardiola.
He acknowledged that Brentford pushed harder in the second half, taking advantage of long balls and wind conditions.
Guardiola noted that his team defended well, limiting Brentford's chances and praising goalkeeper Giorgio Donnarumma for his performance.
Haaland has been impressive, creating clear chances and working hard on the pitch, according to Guardiola, who hopes he will continue to improve his goal-scoring form.
Gardiola also praised Donnarumma, saying he has developed into a top-level goalkeeper at a young age and has the composure and presence to make crucial saves.