The Polish striker continues to be linked with a move to Manchester United as well as Bundesliga rivals Bayern Munich but Zorc says Dortmund certainly want to keep him at the Westfalenstadion despite the heavy interest.
"He has developed into a world-class player with us in the last three years," Zorc told Sport Bild.
"Lewandowski is among the best three strikers in Europe. We don't depend on a transfer fee this term. Why shouldn't he stay another season?"