Lewandowski was expected to leave Dortmund for Bayern Munich in the close-season, but the transfer did not materialise.
The Poland international has been in fine form for Jurgen Klopp's men so far this season, scoring 13 goals in a campaign that appears poised to be his last at Signal Iduna Park.
Bayern, Chelsea, Manchester United and Real Madrid have all been linked with a move for the 25-year-old.
And Lewandowski has revealed that he has come to a decision on his future.
"I will reveal my future next year," he told Sport-Bild. "No one needs to get in touch with me anymore.
"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."
Lewandowski has found the net 88 times in just over three years at Dortmund since joining from Lech Poznan in 2010, and Dortmund are already working to find a replacement of similar calibre.
"There's a clean-cut agreement that Lewandowski will leave in the summer," chief executive Hans-Joachim Watzke said. "We're looking for replacements."
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