Moscow city authorities have refused to allow an opposition march planned for December 15 to take place in the capital's center.
Left Front leader Sergei Udaltsov said organizers had received an official rejection from the Moscow mayor's office.
The authorities also warned the opposition they would not allow unsanctioned rallies.
The December 15 Freedom March was to mark the first anniversary of the mass street protests that erupted after the December 2011 parliamentary elections amid allegations of widespread fraud.
Organizers expected 50,000 people to take part.
Several opposition leaders said they would instead go to Moscow's Lubyanka Square outside the former KGB headquarters to lay wreaths at a monument to victims of Soviet repression.
The opposition is planning marches in other cities across Russia on December 15 as well.
Based on reporting by Interfax, RIA Novosti, and BBC Russian