The 32-year-old admitted on Monday that the third Test against South Africa, which begins at Lord's next Thursday could be his last for England. Pietersen has already retired from limited overs international matches and claimed that it was "hard being him" in the England dressing room.
Cook however was in no mood to discuss Pietersen with his focus fully on levelling the three test series. He said: "Whatever happens is not for me to comment on. We are going to concentrate on our cricket."
He added: "It's down to the board that will get resolved. We as an England side are trying to concentrate on our cricket.
"What happens in our dressing room stays in our dressing room. Look, we have a very important game at Lord's to go we need to win to try and stay number one."