The Spain international has already been linked with a return to former club Atletico Madrid by the British press although he reportedly sat out the weekend's match with a back injury.
Conte was equally non-commital when asked about potentially signing former Blues striker Romelu Lukaku from Everton if Costa were to exit the club.
After the match, Conte told reporters: "I can say that today Costa is a Chelsea player.
"He didn't play in these games because of injury and if he solves the injury and I see in training that he is in good shape it can be possible to see him in the next game against Milan.
"But I can say only this. I speak only for today and today Costa is Chelsea's player. Tomorrow if you ask me if Costa will remain with us, I don't know."
He added: "I do not want to speak about the players of other teams.
"This is not respectful to the club or to their players. I prefer not to speak.
"The transfer market is not the most important thing. The important thing is to build a team - a team that plays in good and bad situations and concentrates and works together."