Mr Macfarlane said: "The Government will not make changes that will impact those who have already made an investment - small or large - under the RET."
"The Government is not suggesting the RET should be scrapped."
Mr Macfarlane said the Government will announce its response to a recent review of the RET in the coming weeks.
"The Government will consider the findings of the panel's review in the context of the costs and benefits of the scheme, the impact on electricity prices and markets and investment issues," he said.
On the topic of Australia's future energy market, Mr Macfarlane said the Government isn't advocating exclusively for renewable energy nor gas or coal-fired electricity.
"Australia's greatest energy strength comes from the diversity of our supply," he said.
"We intend to pursue policies that maintain this diversity.
"Renewable energy will continue to be part of that mix."
To read Mr Macfarlane's full address to the CEDA's energy future event click here.