More than 30 people including opposition leader Konstantin Kosyakin were detained on Friday over participating in an unsanctioned protest and have already been released.
"About 30 protesters who were carrying banners and yelling various slogans were detained," a police spokesman confirmed.
The Moscow police headquarter's press service later said all of those detained have been released.
Dozens gathered near the entrance to Teatralnya subway station in downtown Moscow to protest against the arrest of Sergei Udaltsov, the leader of opposition movement Left Font, who was earlier put behind bars for 15 days for defying police.
Kosyakin was detained after he told journalists that protesters would march to the president's administration. There is information Sergei Udaltsov's wife, Luydmila, has also been taken into custody.