The Argentine striker spoke out on Twitter following City's embarrassing 3-1 defeat at Southampton on Saturday; a result that leaves the current champions trailing Manchester United, who also have a game in hand, by nine points.
"Some days, nothing works the way it should," said Argentina international Aguero.
"This was one of those days. There's no excuse - we need to work hard to forge ahead.
"It all looks a bit grim right now, but I won't believe giving up is an option."
However, City captain Vincent Kompany, who was forced to watch the Southampton defeat from the stands because of injury, believes there is still a lot to play for.
"Our fans sang and stood behind us all game yesterday, despite losing," he tweeted.
"Just reminds me that there will always be a lot to play for. #MCFC !!"
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