The policeman was “stabbed several times in the area of the head” while trying to intervene, local police said.
He underwent “emergency surgery and was put in an artificial coma”, but “died of his injuries” on Sunday, police said.
Olaf Scholz said he was “deeply saddened” by the death following the “terrible attack”.
“His commitment to the safety of all of us deserves the highest recognition,” the chancellor said on X, formerly Twitter.
Christian Lindner, the finance minister, told German daily Bild the death “moves me deeply and makes me angry about what is happening in our country”.
Germany on high alert
“We must defend ourselves against Islamist terrorism with determination, and we will also strengthen the security authorities financially,” he said.
Nancy Faeser, the interior minister, on Friday called for a thorough investigation into the attack.
“If the investigations reveal an Islamist motive, this would be a further confirmation of the great danger posed by Islamist acts of violence,” she said.