People are being urged online to gather at a Sydney beach and incite violence against members of the Middle Eastern community.
The posts were first circulated in the days after Islamic State-inspired gunmen opened fire on a Hanukkah event at Bondi Beach, killing 15 people.
But NSW police are aware of them and have reminded locals they will be ready to take action on criminals "motivated by hate".
"Everyone in NSW deserves to be safe and feel safe," acting assistant commissioner Brendan Gorman said.
"Now is not the time for any behaviour that will cause division in our community.
"The NSW Police Force has zero tolerance for any behaviour that threatens social cohesion in our state."
Police on Monday arrested a 20-year-old man near Gosford after an investigation into the allegedly violent call to action.
He was charged with using carriage service to menace, harass, offend and publicly threaten violence on grounds of race or religion.
Following his arrest, NSW Premier Chris Minns reminded Australians "hate can't beat hate".
"We will not tolerate anyone trying to incite - via the internet or Facebook or social media posts - and attempt to bring our communities together in violence," he told reporters.
"We cannot allow that to happen.
"Racism directed against anybody in our community, is in effect, directed against everybody."
Laws rushed through state parliament in the aftermath of the terrorist attack allow Police Commissioner Mal Lanyon to restrict public assemblies across metropolitan Sydney for two weeks from December 24.
They have also given police powers to demand anyone suspected of committing an offence to remove face coverings.
While gatherings are permitted, police can direct people to move on if they are behaving in an intimidatory or harassing manner, or are likely to cause fear.
The laws have been widely panned by civil liberties and protest groups as an overreach that will not stop anti-Semitism.
A High Court challenge has been planned to fight the reforms.
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