Heavy police presence
A heavy police presence, including officers mounted on horseback, ringed the protesters in an attempt to minimise disruption to peak-hour commuters, some of whom also squabbled with police.
Protesters held placards saying "Dick Go Home & Take John With You" and "Coalition of the Killing".
Police later relented and shepherded protesters as they marched towards the US consulate. Another protest is planned for Friday.
Cheney arrived amid tight security several hours later. He is to meet Howard on Saturday.
Howard has ruled out following Britain's example and cutting troop numbers in Iraq, but his unwavering commitment has him walking through a political minefield towards an election later this year.
Cheney's trip to Australia is meant to reassure Washington's allies that Bush's planned injection of 21,500 more troops into Iraq will help quell violence.
But Britain's promise to soon start withdrawing troops has added to the pressure on Washington's other allies.
Denmark and Lithuania have said they would pull out their much smaller commitments.
"Out of Step," the Sydney Morning Herald said in a front-page headline about Australia's Iraq commitment.
Iraq is a major problem for Howard's conservative government ahead of elections in the second half of 2007, perhaps the toughest of his 11-year tenure.
An opinion poll this week found 67 per cent of Australians either want Howard to set a date for withdrawing troops from Iraq or pull them out immediately.