The Argentine striker points to the evidence from last season, when City overcame a deficit late in the season to pinch the title from under the noses of their city rivals.
Aguero says that Manchester City players still believe that a repeat is possible, despite the club's current slump.
"We have to keep fighting until the end, that's my motto and that's the way we won the Premier League last season," he said.
"In football, everything is possible. We are still in a contest with Manchester United.
"We won the title off them last season and now we're in the fight again.
"We can regain the leadership of the Premier League from them. City have everything to grow and the best is yet to come.
"I say this because I feel the ambition of my team mates in the dressing room, in training and in matches."
Manchester City face Leeds on Sunday for a place in the FA Cup quarter finals.