"The acceleration of cases in NSW isn't growing, which is a good thing," she told reporters on Thursday.
"So, we know that we're having some level of success in reducing the spread. But we have to maintain our vigilance. We are at a very critical phase."
Police Commissioner Mick Fuller says new social isolation rules will last for 90 days and hopefully not longer.
Gatherings of more than two people, apart from immediate family, are banned in NSW as are all non-essential activities
"It is 90 days. People will have gotten the message by then, hopefully," he said on Thursday.
"We won't be talking about the powers, we'll be talking about what does it look like coming out of this."
NSW will change planning rules to help struggling companies in sectors such as hospitality and construction.
"We want to encourage businesses that are going to keep going," Ms Berejiklian said.
"The core of that is to make sure we provide every opportunity for businesses not only to keep going but to make sure that they're accelerating what they can do during this time."
NSW recorded its first COVID-19 death outside of Sydney after a 67-year-old patient at Orange Base Hospital died on Wednesday.
Five of the state's deaths are residents who lived at the Dorothy Henderson Lodge aged care home in Macquarie Park.