Police reported that around 600 people were in the camp area, and that they removed 11 tents. Hundreds of officers were deployed to evacuate the area, while protesters threw paint-filled balloons at them.
Protesters claim that several people were injured in the conflict with police, and reacted with outrage over the decision to clear out the camp.
“The Hamburg police obstructed a registered, legally confirmed gathering, and with their behaviour clearly acted as if in a legal black hole,” camp organizers wrote in a statement.
But police later tweeted on Monday that the administrative court had since supported their decision to clear out the campsite.
"No more overnight stays will be tolerated," police wrote on Twitter.
About 30 more protests are scheduled for the week, with the summit set to run on Friday and Saturday. The Group of 20 (G20) meeting of world leaders is in part especially contentious with the arrival of US President Donald Trump in his first official trip to Germany.