Cllr Macmillan slammed the scotch whisky firm as being 'two-faced' after it lodged proposals to demolish its bottling hall in Paisley while still consulting with around 450 staff over the future of their jobs.
The firm announced plans earlier this month to relocate its operations in Renfrew Road to Dumbarton.
It plans to build a new £40 million facility in Dumbarton, with completion of the new bottling hall and offices scheduled for 2019.
However, Cllr Macmillan said if the building warrant application is approved, Chivas would gain permission to level its Paisley bottling hall as soon as it chose to.
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He said: "The actions of Chivas management are two-faced and heartless - they are treating Paisley workers with contempt.
"On one hand they are still speaking to hundreds of devastated workers about their futures...on the other they have clearly been working for some time on detailed plans to demolish their place of work.
"When the closure was suddenly announced two weeks ago we were told it would take up to three years before the Paisley plant closed down totally - this opens up questions over what sort of timescale the firm really has in mind.
"The company has a rich history in the town, with generations of families having worked there over the past half-century.
"So it is disappointing they would act this way while their Paisley-based staff are still coming to terms with the news and waiting for more information about what their relocation options might be."
Cllr Macmillan recently secured the support of First Minister Nicola Sturgeon Sturgeon to create a Scottish Government multi-agency taskforce to help mitigate the impact of the relocation.
He added he was due to meet with union representatives over the next week and the council will work with all agencies to "mitigate the impact this will have on Renfrewshire families".
(LM/CD)
