Following Atletico's indifferent start to the new season, Aguero has again been linked with a move away from the Vicente Calderon.
The Argentine is said to be top of Chelsea's wanted list, but Atletico - who have already confirmed they rejected big money offers in the summer - insist they are not worried about the constant links.
"We are calm about the future of Kun Aguero," a spokesman told skysports.com.
Atletico are understood to be preparing a new contract offer for Aguero, who has two-and-a-half-years left on his current deal.
Chelsea are currently banned from registering new players in the next two transfer windows, but are hoping to have the punishment suspended pending their appeal.