Mr Barclay said the union represented about 100 members working at the council.
"Our members have been given inadequate information throughout this process and they are upset at how they have been treated," he said.
Mr Williams said he would be meeting the PSA this week.
"All three unions which represent council staff - the PSA, Amalgamated Workers Union and First Union - have been involved during the various consultation phases and the council looks forward to continuing working with them through to the end of the realignment process."
Mr Williams said briefings with unions started in February and the most recent was last Tuesday, prior to the announcement of the final structure to staff.
In Saturday's Rotorua Daily Post, senior Rotorua district councillors Glenys Searancke, Trevor Maxwell and Charles Sturt said they felt for staff who faced losing their jobs in the coming weeks.
Mr Barclay said: "Councillors Searancke, Maxwell and Sturt told media they felt sympathy for the staff, but they sit on a council responsible for this decision."
Mr Barclay said members were unhappy with the council, saying they expected feedback after making their submissions regarding the process, but had received nothing from council management. But he said Mr Williams had agreed to talk with union representatives in the hope he would "take immediate action to initiate genuine consultation with the PSA, our members, and the wider Rotorua community".
"It is clear that cost-cutting has been valued more than the important services provided to the community by the more than 10 per cent of council staff whose jobs are set to go," Mr Barclay said.
Last week, Rob Popata of the Amalgamated Workers Union, which represents about 140 district council staff members, said the union was happy with the way in which the council had treated its workers throughout the process.