Premier Gladys Berejiklian said all the cases recorded in the 24 hours to 8pm on Sunday were connected to Sydney's northern beaches cluster, taking the size of that cluster to at least 83.
The new cases emerged from the tests, which was the highest number conducted in the state in one day on record.
"The government is monitoring the situation almost on an hourly basis. We will consider our position in relation to what Christmas and the next few days look like beyond Wednesday ... it's an ongoing brief," Ms Berejiklian said on Monday.
NSW Health Minister Brad Hazzard earlier expressed his regret Sydney residents were facing "a COVID Christmas" after a raft of restrictions were imposed just days before December 25.
The government has imposed a number of restrictions on the Sydney region, including the Blue Mountains, Central Coast and Illawarra-Shoalhaven, which will remain in place until midnight on Wednesday.
Meanwhile, two people have been fined for visiting Manly on the northern beaches on Sunday without a lawful excuse.
"(It's) very disappointing that after nine months of people living with these restrictions, they still want to run the gauntlet," NSW Police Minister David Elliott told Seven Network.
On Monday, more health alerts were issued for gyms, cafes, restaurants, a nursery and a sports centre across Freshwater, Mona Vale, Newport and Warriewood on the northern beaches, as well as Double Bay in Sydney's east.
NSW Labor said the NSW government should make face masks mandatory on public transport, backed by a number of epidemiologists.
Mr Hazzard said while everyone in Sydney should be wearing masks when shopping, on public transport or when out in the general community the government had no plans to make it mandatory.
"If we have bus drivers having to act like police ... there is already a level of anxiety for them and we don't want to put them in a situation where they will be policemen and possibly getting into the sorts of fights that might happen," he told ABC TV.
Every state and territory has now moved to block Greater Sydney residents from freely entering.
On Sunday, northern beaches residents were put in lockdown until midnight on Wednesday and no-one can enter the region without a lawful excuse.
They are permitted to leave their homes for five basic reasons: to seek medical care, exercise, grocery shop, work or for compassionate care reasons.
Since Sunday people in Greater Sydney, the Blue Mountains, Central Coast and Illawarra-Shoalhaven can have a maximum of 10 in their homes and patrons need to maintain a four-square metre distancing at venues.
Up to 300 people are permitted at places of worship and hospitality venues, while singing and chanting at indoor venues is banned and dance floors are only allowed at weddings.
People are also being urged to avoid visiting any vulnerable friends, relatives or aged-care facilities until Christmas Eve.