Red paint has been daubed on a Jewish commemorative stone in the small town of Löcknitz, police in the north-eastern German state of Mecklenburg-Vorpommern said on Sunday.
The stone and the plaque attached to it was sprayed with paint, the report said. The crime was first noticed early on Saturday.
The perpetrators are unknown, and an investigation is under way.
Löcknitz lies in the far north-east of Germany, close to the border with Poland.