Dubbed Amaze, the 180-metre project drew the ire of pedestrians and cyclists concerned it would worsen congestion issues on the bridge linking the CBD and Pyrmont, and ridicule from the Roads Minister, Duncan Gay, who mistook it for a proposal by the Greens.

"We live in a weird and wacky world when the Greens suddenly decide that a bridge should not be a bridge but should be a garden area," Mr Gay told Parliament this month.

But the proposal, which would take up a third of the bridge's width, was actually being advanced by the Sydney Harbour Foreshore Authority and Planning Minister Pru Goward.

A spokesman for Ms Goward declined to comment on Tuesday when asked directly if the project would go ahead.

The "world-first experiment in environmentally sustainable design", announced in July, was due to be installed on the busy thoroughfare in October.

The spokesman appeared to blame the City of Sydney for delaying the project.

"The Minister is disappointed the City of Sydney has held up approval of the project, at the expense of the pedestrians and tourists who could enjoy the installation, and the businesses in Darling Harbour who rely on outdoor activities such as this to drive customers through their doors," he said.

A City of Sydney spokesman, however, said the council was merely following the normal practice of project approval.

"City staff met with SHFA staff to discuss the application and SHFA agreed to make extensive moderations to their original proposal," the spokesman said.

"Pyrmont Bridge is a major pedestrian and cyclist thoroughfare, with 17,000 people accessing the bridge each day."

Opportunity to place the garden down the middle of Pyrmont Bridge arose after the state government began removing the monorail last year.