Authorities reported 450 new infections on Sunday after more than 500 cases were recorded for three days in a row, the Korea Disease Control and Prevention Agency said.
What authorities are calling a third wave of infections is spreading at the fastest rate in nearly nine months, driven by outbreaks at military facilities, a sauna, a high school and churches.
Prime Minister Chung Sye-kyun said restrictions would be tightened on gatherings and activities seen as prone to virus transmission, especially in the capital Seoul and surrounding urban areas.
"Year-end events and parties hosted by hotels, party rooms, guest houses and other accommodation facilities will be banned outright," Chung told a briefing after meeting health officials.
Saunas and steam-bath rooms with a high risk of mass infection would also be banned as would the teaching of wind musical instruments and singing, he said.
For rest of the country, social distancing rules would also be tightened from Tuesday, he said.
Separately, Chung said the government was talking to parliament about the possibility of new relief funds for households and businesses, which would be the third this year, as the economy struggles.
"Our assessment is that we need the third crisis support fund ... The government will come up with a conclusion on this after discussing with both the ruling and opposition parties."