Some 10,000 people, according to public broadcaster Rbb, took to the streets here Thursday to protest a ruling by Germany's Federal Constitutional Court striking down the rent freeze imposed by the Berlin regional government.
Participants carried signs denouncing property speculators and the decision by the tribunal, located in the western city of Karlsruhe.
Acting on a challenge to the constitutionality of the Berlin ordinance brought by 284 pro-business legislators in the federal parliament, the court said that an existing national rent-control law pre-empted measures at the municipal or regional level.
Thursday's mobilization took place in the densely populated borough of Neukölln, whose status as Berlin's most affordable area has been undermined in recent years by gentrification.
As the mass of the protesters began to disperse, a group of around 400 people entered into confrontation with the large police contingent monitoring the march.
Militants hurled objects at the officers, who responded by charging into the crowd.
Berlin's Social Democratic mayor, Michael Müller, enacted the rent freeze last year with support from the Greens and Die Linke (The Left).
The cap locked the price per square meter of apartment space at a maximum of 9.80 euros ($11.70). It affected 1.5 million homes in Berlin, where 85 percent of people rent.
The initiative was designed to keep housing in the capital affordable after a decade that saw a doubling of rents, fueled by an influx of people, low interest rates and limits to new construction that kept the supply of housing from keeping up with demand.
When the rent cap came into effect, landlords who contravened the rules could faced potential fines of up to 500,000 euros. EFE