The Poland international, who has scored nine goals in 15 Bundesliga game this season, has long been linked with Manchester United as well as a host of Europe's heavyweight clubs.
And there is a suggestion Lewandowski wants to move after showing no great rush to sign an extension to the remaining one-and-a-half years on his current Dortmund contract.
The defending German champions, who are currently hanging on to third place in the table, are therefore concerned they could lose the 24-year-old in a cut-price deal either at the end of the season to sell sooner rather than later.
Club executive Hans-Joachim Watzke told Bild: "As often as I am talking to Robert, I do not have the impression he wants to leave us.
"We will have to make decisions in this case at the end of the season. We may decide on economical factors.
"Would it be best to cash in a big fee? Or would it be even better to keep Lewandowski to ensure we are more likely to qualify for the Champions League with him in our side, as this would guarantee us big income?
"It's a decision we will have to take. It's our decision. It's not something to be decided by others."