A public inquiry is underway into the future of Bristol's Castle Park.
Bristol City Council and developer Deeley Freed want to build on the St Mary Le Port site which would encroach on open space.
Campaigners opposed to move applied for "town green" status for the park to protect it from development.
The £150m plan for the former Bank of England site were due to be reconsidered following a number of protests about the scheme.
Mary Bannerman, from the Castle Park Users Group, said the revamped plans would still see the development "nibbling" at the green space.
"The concern is that the derelict buildings at the Bristol Bridge end do need to be replaced but the council's own developers have a plan to redevelop that area but they do need to take some of the park."
Councillor Helen Holland, leader of Bristol City Council, said the proposed development would use less than 5% of current green area.
"We've got some fantastic green spaces in the city centre but we need to make sure that we do preserve them and that we do make them usable for as much of the day as we possibly can, and at the moment Castle Park isn't really used in that way."
The public inquiry at the Old Council House, Corn Street, Bristol is due to last a week.