Prolific striker Robert Lewandowski will join Bundesliga champions Bayern Munich at the end of the season, while the likes of Marco Reus and Ilkay Gundogan have been linked with moves away from Signal Iduna Park.
Manchester United are reportedly keen to take playmaker Reus to Old Trafford, and both Real Madrid and United are said to be interested in midfielder Gundogan.
Gundogan's contract expires next year, but he has been offered a new deal and Watzke has denied suggestions Dortmund will look to cash in on the 23-year-old.
"We would like to prolong with Ilkay. He has an offer on the table," Watzke told Sport Bild. "The decision will certainly not wait until the summer."
Watzke stressed that the same applies for fellow Germany international Reus and any other Dortmund players that are in demand, but under contract.
"We absolutely do not see the need to sell players who have an existing contract." he said.
