Tires burned at night on the corner of Rigaer Strasse and Liebigstrasse in Berlin-Friedrichshain.
The forces were thrown with stones by strangers, as the police said.
The fire brigade could only extinguish the fire on Monday morning under police protection.
According to the information, no one was injured.
Berlin - In the "Rigaer 94" a partially occupied house was searched by the police last week.
The building complex is a symbol of the radical left scene.
There are repeated violent clashes with the police there.
The police could not initially say whether there was a connection with the events during the night.
dpa
