Costa, 25, has emerged into one of the best forwards in Europe this season and has netted 19 times in La Liga, with only Real Madrid's Cristiano Ronaldo scoring more in Spain.
A number of Premier League clubs have been linked with the Brazilian-born striker's services and now Simeone has added fuel to the fire.
"Atletico has always had a turnover at the striker position from [Fernando] Torres, [Sergio] Aguero... No-one is indispensible," he told Cuatro.
"What's most important is the club. Atletico, as a club, has always survived. About his decision between Spain or Brazil, we haven't spoken about it."
Chelsea are believed to lead the race for the forward.