The Spain international has scored 26 goals in 31 La Liga games this season, which has led to reports claiming that the Blues have already agreed a deal to sign the forward.
Chelsea boss Jose Mourinho has been openly critical of his strikers this season, and Simeone has admitted that it is not unusual to see the Portuguese coach turn his attention to Costa.
"His future depends on him and what he feels is best for his future," AS quotes Simeone as saying.
"It's normal that Chelsea are interested in him. They are an economic power, Samuel Eto'o is getting older and Costa can do his work, but right now he's ours."
Chelsea will face Atletico in the semi-finals of the Champions League next Tuesday.