Eleven group members were arrested on Tuesday after about 40 people marched from Sydney's Hyde Park up William Street, the major route to the city's eastern suburbs, earlier in the day.
NSW Police, including the riot squad and mounted officers, maintained a heavy presence at the event, and the protesters were quickly dispersed.
The march marked the second successive day of action by the group. Ten people were charged with obstruction and disruption offences on Monday when the Sydney Harbour Tunnel was blocked and activists clashed with police in the city centre.
It takes the total number of arrests linked to the protests to 21 after 10 people were arrested on Monday.
Those arrested on Tuesday include nine men and two women, aged between 23 and 74 years old.
Five are from NSW, two from Victoria, two from the ACT, one from Tasmania and one from Queensland.
NSW Police Acting Assistant Commissioner Paul Dunstan said officers would be out in force in response to the protests this week.
"The New South Wales Police Force makes no apologies for the arrests of individuals who are seeking to disrupt the livelihood of Sydneysiders going about their daily business," Mr Dunstan said.
Blockade Australia spokesman Marco Bolemo refused to specify what was planned for the rest of the week, but said the group would target the city and "always vary".
"It's going to be ... powerful again and it's going to continue," Mr Bolemo told reporters on Tuesday afternoon.
He called the police crackdown on the group "absolutely outrageous", claiming officers had violently attacked protesters.
Blockade Australia has argued this week's unsanctioned protests are designed to demonstrate the effects of the collapse of the climate.
It says it has moved away from its prior tactic of targeting ports, which included high-profile disruption at Port Botany, to focus on roads in central Sydney.
The NSW government has clamped down on the civil disobedience, with Police Minister Paul Toole saying on Tuesday he was furious about the protests by "professional pests".
Protesters who disrupt major roadways, ports and railways can now be charged with newly legislated penalties of up to two years in prison and a fine of $22,000.
Mali Poppy Cooper, 22, who locked herself in a car blocking the Sydney Harbour Tunnel on Monday, was one of several protesters granted conditional bail on Tuesday after appearing in court.
NSW Premier Dominic Perrottet described the activists as "bloody idiots" whose actions did not aid their cause.
"You want to push your cause - all you're doing is making people move away from your cause as quickly as possible. It also endangers people," Mr Perrottet told reporters in western Sydney.
Meanwhile, Federal Environment Minister Tanya Plibersek said protesters must respect the law.
"I understand people feel strongly but you've also got a right to make your views publicly known," Ms Plibersek told ABC radio.
"You don't have a right to break the law while you're doing it."
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