It is hoped the regeneration - including partial pedestrianisation of Union Street - could create 5,500 jobs and an extra Â£280m in income a year.
Community councillor Ken Hutcheon said: "There seem to have been opportunities missed and they now seem to be trying to organise a second-class plan."
Councillors have agreed not to comment on the plans before Wednesday.
This is when they will consider the masterplan framework, from consultants BDP.
Mr Hutcheon said: "Now that the councillors have been asked to say nothing about it I am even more worried."
Scott Mackenzie, director of architecture at BDP, previously said the proposals were "imaginative, transformational and challenging."
A masterplan for Aberdeen city centre risks being a "second class" option, according to a community campaigner.