The Poland international is a £10 million target for Real.
"I'll only think about it once I have received a concrete offer," the 26-year-old right-back told Przeglad Sportowy.
"I am a player who only identifies himself with the club he is under contract to, so I'm only thinking of Borussia, who on Saturday are hoping to win the Cup final.
"And I am in tune with the club. Last summer, shortly after my contract extension, I bought a house near Dortmund."