NSW Police are on high alert ahead of more planned protects by climate activist group Blockade Australia in Sydney next week.
Acting assistant commissioner Paul Dunstan said police will be out in force across the city.
"This group remains intent on causing significant disruptions next week to motorists and members of the public through reckless and dangerous activities," he told reporters on Thursday.
"This group is hell-bent on the disruption of Sydney. I urge anyone that is considering participating in this activity to please reconsider.
"Any person blocking a roadway, or a railway line or interfering with our ports will be arrested."
The renewed call for protests come after police arrested eight Blockade Australia activists in a Colo property on Sunday and seized items including barrels filled with concrete and chains.
Police said the property was being used as a training camp for string of co-ordinated protests in Sydney.
The activist group said it would not be deterred "in the face of dramatic repression by police" with a week of events planned from Monday to Saturday.
Det Supt Dunstan said a "highly visible" police operation would cover major roads, train stations, ports and other "sites of significance".
He called on the community to alert police about any "suspicious activity" such as roadblocks being set up or people climbing on structures.
The protest group has previously blocked major Sydney roads, tunnels and critical ports - specifically Port Botany - often capturing footage of themselves suspended off structures and sharing it online.
Laws were passed in NSW in April to deter protesters who face up to two years' jail and $22,000 in fines, with several arrested then released on bail in recent months.
Human Rights Watch on Wednesday criticised NSW authorities' response as "disproportionately punishing climate protesters in violation of their basic rights to peaceful protest".
But Det Supt Dunstan said police had been lawful in their conduct.
"Public safety is our peak concern and ensuring that roads are open and disruption is minimised," he said.
