Lewandowski on Tuesday (AEST) declared that "my story is over" at Bayern Munich after he refused to sign a new contract with the Bundesliga champion.
The prolific Poland captain has made no secret of the fact he wants to join Barca.
Yet Tebas stated the Catalan giant would not be able to afford the striker as they must cut their cloth accordingly after getting into big financial trouble.
Tebas believes the Blaugrana will have to allow one of their most valuable players to leave in order to make a move for Lewandowski.
He said: "Barca already know what they have to do if they want to sign Lewandowski.
"They know our economic control rules perfectly. It's to avoid major economic problems. I don't know if they will sell [Frenkie] de Jong or Pedri.
"They know what they have to do, sell assets. Barca have had many accumulated losses in recent years, some that could have been avoided, and they have to fill the pantry.
"Just like [Real] Madrid has filled their pantry, Barca's is empty. Today they cannot sign him."
Lewandowski told reporters at a Nations League news conference on Tuesday when asked about his future: "It's a big question.
"I don't like being in this situation. What is certain at the moment is that my story at Bayern is over. I don't see any chance of continuing my career at this club.
"Let's see what we can do in the next two weeks, I don't want to continue and I would like to focus on Poland.
"After the Nations League we will have time to talk about the situation, but I don't see any possibility to continue at Bayern.
"Bayern is a serious club and I hope they will not keep me just because they can. A transfer is the best solution for all parties."