Ex-Dortmund forward Lewandowski, who has scored 23 goals in his first season with Bayern, finished the match as a dazed figure and spent the night in a Munich hospital after colliding with Langerak in extra time during Dortmund's German Cup semi-final win in Munich.
German daily Bild reports that Langerak sent Lewandowski a text message to apologise and says he hopes the Poland striker will be able to face Barcelona in the Champions League's semi-final next Thursday (AEST).
"Robert and I are friends and of course I am sorry for what happened," said Langerak, who was outstanding against Bayern.
"I hope he can play as soon as possible. Anyone who knows me knows it wasn't intentional and that I wanted to clear the ball."
Bayern chairman Karl-Heinz Rummenigge is hopeful Lewandowski will play with a mask at Barcelona's Camp Nou.
