Protesters then lay down in the street in front of the New York Stock Exchange, as though they were dead.
The protests are part of an global two-week campaign coordinated by Extinction Rebellion, a campaign group that rose to prominence in April when it disrupted traffic in central London for 11 days.
The protests began on Saturday when protesters occupied a shopping mall in Paris.
The group said the protests Monday were taking place in 60 cities worldwide.Both directions of the bridge were re-opened around 8:30 a.m.
"I don't know that shutting the city down necessarily wins you many friends", Victoria premier Daniel Andrews said. He said police had also been stopping and searching activists. Other spontaneous protests also popped up elsewhere in the city - including protesters playing dead on Dam Square. "What this means is that the government would rather arrest people than take real action on climate change", one protester told CP24 on Monday afternoon.
The group has scheduled non-violent protests chiefly in Europe, North America and Australia over the next two weeks.
The disruption comes one day after dozens of Extinction Rebellion protesters were arrested after participating in Extinction Rebellion demonstrations around the country. "We've had 4,000 rebels sign up and say they are willing to be arrested - which is a huge increase on the number arrested in April of 1,000 [sic]".
Among those arrested was 81-year-old Sarah Lasenby, a retired social worker from Oxford.
A few hundred other protesters have camped out in 40 tents at the gates of the Spanish Ministry of Ecological Transition in Madrid.
"And I'm doing everything I can to help those three demands of Extinction Rebellion - the total truth, to commit to zero carbon emissions by 2025 and do what's necessary, and set up a people's assembly and determine how we achieve that".
Blockade protests for more action against climate change on Stadhouderskade and elsewhere in Amsterdam on Monday ended at around 9:00 p.m., the Amsterdam police said on Twitter.
On Saturday, London police used a battering ram to break into a building used by Extinction Rebellion, seizing protest supplies and arresting 10 people on preemptive charges of suspicion of conspiracy to cause a public nuisance.