Lewandowski feels cheated
The 24-year-old striker, who has been heavily linked with a move to Bayern Munich this summer, is expected to stay for the final year of his contract at Dortmund.
But, speaking to Polish newspaper Rzeczpospolita, Lewandowski says he feels cheated by members of Dortmund's management.
Lewandowski said: "If someone says something, he should keep his word. I'm not saying it's only about the transfer, but other things we have discussed with management and that has not materialised.
"It turns out that words spoken straight into my eyes were untrue. No matter how hard I will train and what I will do, the feeling that I've been cheated will still be there.
"Maybe that word is too much, so for now I will say I'm disappointed."
Lewandowski featured in Dortmund's German Super Cup win against Bayern Munich at the weekend.