Police officers took up positions in front of the beaches of Copacabana, Ipanema and Barra da Tijuca on Saturday, dpa news agency quoted news portal G1 as saying in a report.
"The progress of the epidemic is leaving us in a more difficult situation," said Mayor Eduardo Paes.
"Either we are aware of it and we respect lives, or we are going to live in an unmanageable situation in the next few days," he added.
He announced further measures to contain the measures in the coming week.
As of Sunday morning, Brazil's overall caseload and death toll stood at 11,950,459 and 292,752, respectively.
After the US, Brazil is the second country most affected by the pandemic worldwide.
Last week, the country reported over 90,000 new single-day infections, and around 3,000 deaths.
According to a poll by the Datafolha institute, 79 per cent of Brazilians said the pandemic was out of control.
President Jair Bolsonaro, however, has repeatedly downplayed the coronavirus' seriousness and opposed any far-reaching protective measures.
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