The Argentina international's deal ran until 2019 but he has signed a one-year extension which will keep him at Manchester City until the summer of 2020, when he will be 32.
Pep Guardiola is more concerned about getting his leading scorer back to his best in the key games. Of his last 39 goals for the club, only two have come against teams in the top six.
Aguero faces Tottenham today in a must-win game for City having drawn a blank in the game at White Hart Lane – City's first defeat of the season – and also against Chelsea, Liverpool and Everton. He missed the games against Manchester United and Arsenal because of suspension.
Sergio Aguero has signed a one-year contract extension at Manchester City
Guardiola had dinner with Aguero and his representative in Manchester on Thursday but the City boss denied they had talked about his contract and said it was just a social occasion.
"Sergio earns enough to take his manager out for dinner," he joked. "We didn't talk about his contract. He has already signed a contract extension. Sergio will be here until he decides to be here. He's our best striker.
"We have a problem with goals so we need him. What I want is to help Sergio to play better, as best as possible. That is my target.
Pep Guardiola wants Aguero to rediscover his ruthless streak
"He knows about his scoring record against the top clubs and I know that. He has not scored against the top teams but we have to help him score against them.
"He's missed seven games through suspension this season which is lot for a non-aggressive player like Sergio, but sometimes he has had chances. Against Chelsea he had many chances. In the last game at Everton there was the cross for Sergio but, nothing, he didn't arrive there."
Guardiola hopes the arrival of Brazilian wonder boy Gabriel Jesus, who is set for his debut today, can help Aguero.
"They can definitely play together," he said. "Gabriel who likes to run in behind, he attacks the goal and he can play central, or a little bit left. He has played in both positions for Palmeiras and in the national team."
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Gabriel Jesus completed his £27million move to Man City this week
Guardiola has taken the blame for Claudio Bravo's struggles this season saying he has made too many changes to the defenders and it has not helped communication.
"I'm willing to take all the responsibility as a manager," he said. "Maybe I'm not good enough for the players. It is the manager's job and the player's job so we have to accept the criticism.
"How do we get the best from Claudio? We need to do well in the [penalty] boxes and be stronger. And we will be stronger in front and the back."
Asked if he expected more from Bravo he replied: "From myself too."