The 21-year-old, who has netted 42 league goals in 112 appearances for the la Liga side since arriving from Independiente in 2006, had been linked with moves to Chelsea and Inter Milan earlier this summer.
Later reports suggested Premier League champions Manchester United were keen on acquiring the Argentina international's services as they attempt to find a replacement for Real Madrid-bound FIFA World Player of the Year Cristiano Ronaldo.
While the Red Devils' North West rivals Liverpool were believed to be interested in the front-man, along with Valencia goal-getter David Villa, as they seek support for talisman Fernando Torres.
According to The Sun on Tuesday, Carlo Ancelotti's Blues have been given 24 hours to stump up the £50 million asking price for Aguero before he becomes cup-tied in the Champions League until the New Year.
However, Atletico president Enrique Cerezo insists the club are not interested in selling their prize asset, particularly as they would now have next-to-no time to find a suitable replacement before the transfer window slams shut.
"We do not want to sell and we are calm about everything," he said in Sport.
"Anyone who wants our players knows what to do, provided the player wants to leave.
"If they choose to go and a club wants to sign them, then there is nothing I can do about it."
