The rules will come into effect from 12.01am on Saturday.
"Can I stress that we really want everybody to follow these orders, to make sure that we contain the virus within these local government areas," the premier said.
Ms Berejiklian said that NSW Chief Health Officer Dr Kerry Chant regards the number of cases in Sydney's south-west and west as a "national emergency".
Ms Berejiklian said the state government crisis cabinet met this morning to tighten restrictions.
She urged workers in western Sydney to check if their occupation made them essential workers.
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NSW Chief Health Officer Dr Kerry Chant regards the number of cases in south-western and western Sydney as a 'national emergency'..(9News)