The 25-year-old recently announced he would sign a contract with Bayern Munich in January after Borussia Dortmund put a block on the move during the summer, only to claim shortly afterwards that he had been misunderstood and no agreement had been reached.
In the build-up to England's qualifier with Poland, Lewandowski put Chelsea, Manchester United and Arsenal on red alert by admitting he would like to play in the Premier League in the future.
|14/1||Dortmund are 14/1 with Coral to win the Champions League|
But Lewandowski now insists any fresh approaches from clubs will be pointless as he has made up his mind.
"I am feeling very well at Dortmund, but I want a new challenge next season," the 25-year-old told Sport Bild.
"I can only say one thing about my future and that's that I will announce my decision next year.
"No club has to bother with a fresh approach. I am focused on Dortmund and will not let anything distract me."
Lewandowski has been in fine form so far this season, scoring 13 goals in 17 appearances in all competitions.