The 24-year old Polish striker is again being linked with a move to England following Manchester United's interest in him last summer but Watzke insists there is no financial reason to offload the man who has netted nine Bundesliga goals this season.
"Just to make one thing clear, we alone will make the decision [on whether or not he will be sold]," he told Kicker.
"But of course we will discuss it with him.
"It is simple math. Having Lewandowski play one more season could make more sense economically than to cash in a huge transfer sum. We are under no economical pressure to act."