Jenny Olsen, a member of the TPP Action Group, said the 5pm protest had succeeded in its aim.
About a dozen protesters linked to the group held up placards urging the proposed free trade agreement be scrapped.
Several passing motorists tooted their support.
Mrs Olsen said only a relatively small proportion of the proposed agreement dealt with trade in goods, including dairy products.
Much more of the agreement involved intellectual property, copyright and finance-related matters.
The Government's drug-buying agency Pharmac could be adversely affected, and the agreement was also likely to reduce New Zealand's ability to reach its own policy solutions, including over potential sharemarket controls, she said.
Prime Minister John Key told Radio New Zealand he was ''very, very confident'' the TPPA could be completed in a way that could be ''very advantageous'' to New Zealand.
A further TPPA-related protest is planned for 10.30am today, near the Dunedin Railway Station.
