Some 4,000 protesters gathered in Moscow's Pushkinskaya Square, about a mile north of the Kremlin, on Saturday, police told Sputnik
At least three officers were sprayed with white plaint after protesters threw a can at the riot police, a Sputnik correspondent said.
The police were eventually able to push the raving mob away from the square's landmark Pushkin monument and clear the area. By 4 p.m., some 2,600 people had left the square by subway, the transport authority said on Telegram.
"We ask you to delay travel to the city center," the authority said, adding people should follow social distancing rules.
Bus traffic was slow near the Pushkinskaya and Manezhnaya squares and adjacent Tverskaya Street in the late afternoon, affecting some 20,000 passengers, the city transport authority said.
The central Strastnoy Boulevard and nearby streets were similarly blocked by protesters, causing bus routes to be temporarily diverted.
The riot police attempted to disperse the crowd and used batons. The demonstrators responded by throwing snowballs at law enforcement officers and picking up fights with them. Some of the protesters later left the square, and the riot police followed them.
In addition, some protesters were detained at the Lubyanka square, according to the correspondent.
Moscow's health authority said at least 19 people who had tested positive for the new coronavirus violated the mandatory quarantine to attend the places of gatherings.
"According to the Social Monitoring app, there are 19 people at the unauthorized event in Pushkinskaya Square who have COVID-19. These people have been tagged for quarantine breach," it said.
"About 15 children were detained here in Moscow, many of them are already released. Many were also released in the [Russian] regions," Kuznetsova said, adding that released children are handed over to their parents or legal representatives.
Nationwide protests were called after jailed opposition activist Alexey Navalny was detained last Sunday upon arrival from Germany, where he was treated for his alleged poisoning. The 44-year-old was placed in custody for 30 days for violating probation terms on an earlier embezzlement conviction.