The Poland international has been linked with several clubs throughout the summer, but while he revealed that he was happy at Borussia Dortmund, the 24-year-old has refused to rule out a move to Bayern Munich.
When asked about a possible move to Bayern Munich, Lewandowski told Bild: "That will always be interesting and you have to consider it. It is such a big club.
"I have another two years on my contract. This is a long time. I don't have to decide today if I extend it or not. But, like I said, I only concentrate on Borussia right now."
Lewandowski has scored 39 goals in 89 appearances for the German champions.