Plans are under way for a so-called "Dissenters' March" in Samara during the May 18 summit. In the past months, several such marches were forcefully broken up by police in different Russian cities.
"Critical voices must be able to express themselves," government spokesman Thomas Steg said ahead of the summit, which Putin and German Chancellor Angela Merkel will attend.
"In talks with the Russian president, we always stress the importance of fundamental basic rights, including the right of assembly," Steg said.
Last month, Germany - which holds the rotating EU presidency - condemned as "unacceptable" the Russian police response to protests in St. Petersburg, during which officers clashed with demonstrators, detaining more than 100 of them. Reporters for German public television stations were among those detained.
Next week's demonstration would be the latest in a series of such marches called by various opposition movements, the most prominent of which is the United Civil Front led by ex-world chess champion Garry Kasparov. Of the five such marches held so far, four have been forcefully dispersed by police, including beatings and large number of detentions. The first, held in Moscow in December, was restricted by an overwhelming police presence.
Also this week, a court in Samara ordered an organizer of anti-government protests imprisoned, activists said - just days before the protest march at the summit there was scheduled to be held.
Opposition leaders said that was the first time an activist was given a significant prison term for organizing protests and said it was part of the government campaign to intimidate dissent ahead of the summit.