Dortmund face Arsenal on Wednesday at Borussia's Westfalenstadion in the UEFA Champions League, but the 25-year-old Lewandowski has said he will leave when his contract expires in June.
"I want to experience something new next season even though I feel very well in Dortmund," the Polish striker told magazine Sport Bild having joined Dortmund in July 2010. "I will announce my decision next year."
Having last season become the first player to score four goals in a Champions League semi-final, Lewandowski has already scored nine goals in 11 league games this season. For the rest of the season, he has said he now wants to focus on playing well for last season's Champions League finalists Dortmund without being further distracted by the subject.
The Bundesliga's top scorer, Lewandowski has said he wants to "win titles" for the rest of his stay with a Dortmund team which is "more consistent" and with "greater firepower" compared to last season.
According to FIFA regulations, Lewandowski can announce his future destination from 1 January and has been heavily linked to European champions Bayern Munich, who he wanted to join at the end of last season.
In a bid to keep him, Dortmund gave Lewandowski a significant pay rise for the last 10 months of his contract and Dortmund CEO Hans-Joachim Watzke has confirmed a "separation agreement".