The forums were an opportunity for members of the public to speak to the council on matters of concern.
Mr Guy said the change would give meeting chairmen the discretion to deny people the chance to speak.
He said an Auckland lawyer had addressed the new council in a workshop on the open forums.
The council's meeting rules currently allow chairmen to accept a major item as a late item when, for practicality and urgency, it was unreasonable to delay discussion.
Minor matters could also be discussed without a decision being made, he said.
Mr Guy said the councillors' open forum was originally introduced because of concerns about the "incremental creep'' in which discussions on important matters were taking place outside of public meetings, such as in the councillors' lounge.
He said the proposals at today's meeting were not compatible with the new council's intention to take the community with them. The low election turnout was partly because the public felt disengaged from the council.
"Here we have the new council proposing to restrict these opportunities.''
Mr Guy was also concerned about the proposal to replace the Tauranga Airport Board with an "advisory group''.