The Gabon striker has been at BVB for three years, scoring 60 goals from 101 Bundesliga appearance and, unsurprisingly, some of Europe's top clubs have expressed an interest.
Manchester City have been linked but it is Real Madrid who are thought to be at the front of the queue, as the former Saint-Etienne forward has expressed a liking for the Bernabeu outfit in the past.
Dortmund do not want to lose their star man but Watzke has made it clear they would not hold back the player if he wanted to move to Real.
"If someday there is something from Real Madrid, who he has an affection for, we have to talk about it," he told Sky. "But this [transfer] will not happen automatically.
"We want him to stay with us. As opposed to the players who left us recently, he has a long contract which runs until 2020. There is no pressure at all. And I am not under the impression that he wants to move."