The Polish star has long been linked to Bayern Munich and he is widely expected to move to the Allianz Arena next summer.
Last month, Lewandowski stated he still has a desire to play in England and that he was yet to choose his next club, owing to speculation that Manchester United, Manchester City, Chelsea, Arsenal or Tottenham could pull off a cut-price deal.
However, the striker now insists that the decision on his future has been made.
"I will reveal my future next year. No one needs to get in touch with me anymore," he told Sport-BILD weekly.
"I have decided what I am to do. I simply want to have a new challenge next season, despite the fact I am feeling very, very happy being at Borussia Dortmund."
The 25-year-old joined Borussia in 2010, but he is out of contract at the end of the season, meaning he is able to leave on a free transfer in the summer.