The striker has caught the attention of both Manchester clubs with his goalscoring performances for the reigning Bundesliga champion, while Bayern Munich and Juventus are also believed to be interested in signing the 24-year-old as well.
"Robert has made his decision. Only he decides when he will make his decision public, though," Kucharski said on a Polish talkshow.
"Those who have followed Robert's career will realize that he's never stayed at a club for longer than two seasons. He's already in his third season at Dortmund. Read between the lines and you'll know what this means."
The striker has a contract with BVB until the summer of 2014.