Caps on the country's biggest polluters should only be the first step in efforts to reduce emissions, according to the Greens.
Party leader Adam Bandt said the government was unwilling to go even further in lowering emissions and phasing out coal and gas despite broad public support for the measures.
The Greens and the government reached a deal last week to pass Labor's safeguard mechanism, which aimed to cap the emissions of the 215 biggest polluters by 4.9 per cent each year until 2030.
But Mr Bandt said the mechanism was only the beginning and more action was required.
"The penny hasn't dropped yet from the government that they could actually go even further than what we've been able to get them to do, and they'd still have the support of the people," Mr Bandt told an Australia Institute event on Tuesday.
"It was a real effort to get (the government) to agree to understand that the pollution coming from coal and gas is the issue, and you can't deal with everything by way of offsets."
As part of the deal with the Greens, a ceiling of 140 million tonnes has been set for pollution levels, with the limit set to decrease over time.
The safeguard includes a "pollution trigger" that requires the climate change minister to consider whether a coal or gas project would go ahead if it risked blowing out the pollution ceiling.
The safeguard, set to reduce emissions by 205 million tonnes by 2030, is a key part of government efforts to reduce emissions by 43 per cent based on 2005 levels by the end of the decade.
Mr Bandt said allowing large polluters to purchase offsets for their emissions was not effective.
"Where the government still wants to go is not consistent with what the science requires," he said.
"We've shown that it's possible to start reining in the coal and gas corporations but do we need to do more? Yeah, absolutely we do."
Opposition Leader Peter Dutton said the government's renewables plan in the lead-up to 2030 was not sustainable and called for small-scale nuclear power to be a possible option.
"The government's renewable plan by 2030 needs to build 40 wind turbines every month and construct 22,000 solar panels every day," he told the COSBOA National Small Business Summit.
"To be honest, it's just not realistic. And there's certainly no regard for costs."
He said the multi-billion dollar cost would be passed on to consumers instead of being absorbed by companies or the government.
