Councils across Devon and Cornwall have been considering proposals to effectively end the 100% council tax discount for hard-pressed families from April, including those out of work.
The possible change has been compared to the introduction of the poll tax and could mean households that pay nothing face huge bills.
Tory-led Cornwall Council is considering a 25% cut to so-called council tax benefit, which means asking residents to pay at least a quarter of their bill.
By contrast, Conservative South Hams and West Devon councils – which were considering a 30% and 25% cut respectively – have postponed the reform for a year.
Speaking to the regional newspaper political editors at Westminster, Mr Pickles pointed out that many councils had avoided making low-income households pay. But others were planning to tax the poor, he said.
"That struck me as being obscene," he added. Councils could instead focus on helping people find work, he said.
"I thought it was a singularly unambitious scheme, just taxing people who are in receipt of council tax benefit rather than helping them get into work, dealing with mistakes and fraud."
He added: "Their job is not to tax the poor. It's to help the poor.
"That's why I'm so angry with these plutocratic city leaders who are not prepared to get alongside the poor. Who are happy for people to stay on benefit."
He said he was considering using his powers as Secretary of State to order councils not to impose council tax charges on the unemployed.
Latest Government figures show 157,000 people in Devon and Cornwall claim council tax benefit.
The council proposals follow a 10% Government cut to rebates available to councils, and giving local authorities control of council tax benefits for the first time. But the cut has left councils with a black hole to fill. For example, Cornwall Council has to find £6 million and Plymouth City Council has a £2 million shortfall.
Much depends on the grant handed down by Whitehall to councils from April. The latest local government settlements are expected to be announced this week.
Councillor Alex Folkes, deputy leader of Cornwall Council's Liberal Democrat group, said the poorest households in the area would be worse off by up to £950 a year, and plans could lead to "the social cleansing of areas with higher property prices".
He added: "Council tax benefit is only given to those who really need it, mostly people who are in low-paid work or full-time carers. Trying to get more money out of people who have none will bring Christmas cheer to bailiffs but no-one else."
