Potential rioters should have their movements restricted or be made wear electronic ankle tags, German Interior Minister Thomas de Maizière has said.
He was outlining ideas to prevent a repeat of the mass rioting which marred the G20 summit in Hamburg.
Some 20,000 police officers were deployed and nearly 500 were injured as rioters torched cars, looted shops and threw stones and petrol bombs.
Mr de Maizière drew a comparison with the restrictions on football hooligans.
The mayor of Hamburg, Olaf Scholz, apologised to residents this week for the unrest, which he blamed squarely on violent elements among the protesters.
“The responsibility for this violence does not lie with the summit or the police, it lies with those who committed this violence, the criminal mob who did not care at all about the people in our city and whose only goal was to commit violence and to destroy,” he said.
More than 100,000 demonstrators are believed to have attended protests during the 7-8 July summit, many of them peaceful.
Speaking to German media, the interior minister said rioters should not be allowed to attend rallies.
Instead, they should be made to report to police and wear tags if necessary, as should “highly aggressive so-called football fans”.
Mr de Maizière also called for tougher action to be taken against squatters, clearing occupied houses immediately.
Hamburg, long known for its squats, has a tradition of rioting by the far left.
Clashes also broke out at this year’s May Day protest in the city, while in 2008 cars burned as extremists battled police on the streets for several hours.
It meant Hamburg police were already aware of the potential issues ahead of the G20, drafting in police from around the country.
Is thought that other leftist militants arrived in the city from across Germany and beyond.