Russia, where the cases of the virus have risen rapidly this month, has shut down whole cities and regions to slow the contagion, inflicting economic pain in some households as businesses have been forced to close.
Vadim Cheldiev, a singer in the southern region of North Ossetia who has 10,000 followers on social media networks, led Monday's protest there and called for the resignation of the local government and the region's head.
Hundreds of unmasked protesters could be seen in footage from the rally tightly packed into a square on Monday with police officers in riot gear looking on.
In a video, Cheldiev said there was no coronavirus threat and that the authorities were using it as a pretext to expand their control over citizens.
North Ossetia has recorded 177 confirmed cases of the new coronavirus and two deaths, while the nationwide case tally stands at more than 52,000 with an official death toll of 456.
Police took Cheldiev into custody and a court ordered he be held for two months and fined him 75,000 roubles ($975) for spreading false information about the outbreak, a court was quoted as saying by the RIA news agency on Tuesday.
He is being investigated for allegedly using violence against a member of the authorities, calling for mass protesters and spreading false information about the outbreak, it said.
Cheldiev's lawyer said his client did not agree with the allegation of violence, but was cooperating with the police, the TASS news agency reported. It was not immediately clear what incident the allegation related to.North Ossetia is a poor region in Russia's turbulent North Caucasus and has an ethnic Ossetian majority and a Russian minority.