Doku opened the scoring with a curling strike from the left flank before further goals from Erling Haaland and Omar Marmoush sealed the victory as City kept pace in the title race.
The 23-year-old has now scored in three consecutive matches for the first time in his club career, following goals against Everton and Southampton. His recent form has strengthened City during the closing weeks of the season, with Guardiola praising both his talent and mentality.
Asked whether Doku could eventually match the impact of Vinicius and Yamal, Guardiola responded positively.
"Yeah, for sure," Guardiola said. "And always accept being pushed. Always accept that. That is so nice. We are really pleased. Now he is winning games, but he has always been really, really good."
The City coach added that reaching the top level depends largely on ambition and mentality rather than technical skill alone.
"It depends on your mentality," Guardiola said. "I want to become one of the best wingers in the world. Otherwise you stay in a comfort zone. Jeremy has always had the dribbles and the quality, but to become one of the best of the best you have to keep pushing."
Doku recently admitted that a lack of goals had previously prevented him from being regarded among the game's elite attackers, but the winger says his confidence has never changed.
"I've always been a confident player," Doku said. "Now the goals are there, but in terms of play I've always played like this. I know where I can be and where I want to go."
His goal against Brentford - curled into the far corner after cutting in from the left - mirrored similar finishes he produced earlier this season, including strikes against Everton and Liverpool.
Doku also revealed the goal carried personal meaning as he dedicated it to his father on his 60th birthday.
"I felt like I hit it well," he said. "Afterwards, to see it go in was good. It's grace from above. I'm just grateful and I'll continue to work hard."
The Belgian, who joined City three years ago, says additional personal training has helped him maintain consistency despite the heavy physical attention he receives from defenders.
"I just work hard, try to train hard, more than just at the club," he said. "I do personal training just to stay fit and reproduce those efforts every game."
With three league games remaining, Guardiola said City remain focused on pushing the title race to the final day as they prepare for matches against Crystal Palace F.C., AFC Bournemouth and Aston Villa F.C..
"Three games left and we go for it," Guardiola said. "We have to win our games and do what we have to do."
