NSW residents returning from coronavirus-hit Victoria must now undertake two weeks of hotel quarantine, while young people across the state are urged to rein in their social activities.
Entry to NSW from Victoria is now restricted to flights landing at Sydney Airport, except for border community residents with permits.
Those returning through the airport will be sent into 14 days of hotel quarantine at their own expense, alongside those returning from overseas.
The changes were announced earlier in the week in response to the escalation of the COVID-19 outbreak in the southern state and came into effect on Friday.
NSW Police Commissioner Mick Fuller said hotel quarantine had been one of the state's most effective tools in preventing the spread of COVID-19.
"Make no mistake - mandatory hotel quarantine has undoubtedly saved many lives, particularly among our vulnerable community members, and will continue to do so as we navigate this public health threat," he said in a statement on Friday.
It comes as NSW recorded 11 new COVID-19 cases in the 24 hours to 8pm on Thursday, including one who attended The Apollo restaurant in Potts Point and eight who are close contacts of known cases.
One case, a female in her 60s from Sydney's southwest, is still under investigation, while one new case acquired in Victoria is in self-isolation.
A man in his 20s, who was confirmed as a case on Thursday, attended several Newcastle venues between July 31 and August 2 including Bennett Hotel in Hamilton, Sydney Junction Hotel in Hamilton and the Wests New Lambton club.
Anyone who attended those venues between specific times should immediately self-isolate for 14 days from the day they attended and get tested.
The man also visited the Greenroof Bar and Restaurant in Hamilton, the Queens Wharf Hotel and Sushi Revolution in Hamilton, and was among 2570 spectators at the Newcastle Jets-Western United match on Sunday at McDonald Jones Stadium.
Anyone who visited those venues on those dates is considered a casual contact.
The man is a close contact of a Newcastle teenager whose diagnosis shut down his high school and sent two football teams into self-isolation.
NSW Health on Friday said a household contact of a previously reported case attended St Francis Xavier's College in Hamilton East on August 3, 4 and 5. The school is closed for cleaning.
Other previously confirmed cases - two Sydney men in their 20s - attended several venues while potentially infectious.
One dined the Jambo Jambo African restaurant in Glebe on July 31 from 7pm to 8.30pm and anyone who attended the restaurant at that time should self-isolate and get tested.
The man also visited several other inner-Sydney venues between Friday and Sunday but patrons at these places are classified as casual contacts.
The other attended Penrith Plaza, Master Hot Pot in Canley Vale and BBQ City Buffet in Bankstown on August 1, and those who were at those venues should be alert for symptoms.
NSW Premier Gladys Berejiklian urged young adults to rein in their social lives.
"We are on a knife-edge," she told Triple M radio on Thursday.
"To the young people, try and modify the number of places that you go to."
The Australian Medical Association, meanwhile, is encouraging NSW residents to wear a mask in public at all times despite current state government guidelines.
The NSW government recommends mask use where social distancing is impossible, as well as for public-facing employees, religious worshippers and those who live near COVID-19 clusters.
The elderly and those at high health risk should also wear masks.
Australian Associated Press