Sydney on Thursday before the arrival of Vice President Dick Cheney, underlining divisions within one of Washington's firmest allies over the unpopular war.
A police spokeswoman said seven people were arrested when police barred up to 200 Stop the War Coalition protesters from marching through Australia's largest city, demanding Prime Minister John Howard pull troops out of Iraq.
A heavy police presence, including officers mounted on horseback, ringed the protesters in an attempt to minimize 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 toward the U.S. 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 toward an election later this year.
"Mr Howard is enduring a perfect storm on the alliance and Iraq at the moment, a series of unexpected events which are combining to make for difficult sailing," Michael Fullilove, global issues director at the Lowy Institute think tank, told Reuters