The champions currently sit 12 points behind league leaders Manchester United, with many already claiming that the Red Devils have the title wrapped up.
However, Aguero believes that City, who recovered from a large points deficit to win the league last season, should not give up just yet.
"Let's take it step by step," Aguero told The Sun. "Take the FA Cup, each victory means we are a step closer to winning the competition.
"It's about keeping focused and trusting in our game. That applies to all our remaining Premier League games too.
"Can we still win the title? I'd like to believe so. We can't give up, even though it looks tough."
City travel to face Aston Villa on Monday.