"This is not a climate negotiation summit. You don't negotiate with nature. This is a climate action summit."
Nearly 70 countries - about two-fifths of those signed up to the Paris Agreement - have indicated they will increase climate action.
But Prime Minister Scott Morrison is holding fast to Australia's target of cutting emissions by 26-28 per cent from 2005 levels by 2030.
"I'm committed to what I took to the Australian people; that was 26 per cent for 2030 and that's what we'll achieve," he told reporters in Chicago, where he gave a foreign policy speech while the climate summit was opening in New York.
Foreign Minister Marise Payne represented Australia at the climate summit.
Asked if he felt the need to say something about longer-term targets in response to Mr Guterres, Mr Morrison said: "Not at this point."
The question of emissions cuts has been a vexed one for the coalition and was part of the reason the Liberals dumped Malcolm Turnbull as leader a year ago.
'It's about plastics'
Instead of stronger emissions targets, Mr Morrison is focused on practical environmental actions, like reducing plastic waste and cleaning up oceans.
"On Wednesday, when I give the national statement in the UN General Assembly, I'll be focusing very much on Australia's response to the global environmental challenges, which isn't just climate change," he said.
"It's about plastics, it's about oceans, it's about recycling."
He also suggested China should now be treated as a developed - rather than developing - economy in addressing global environmental challenges.
"If you look at the projections on emissions out to 2030, what you'll see is Australia meeting its commitment, you'll see the United States ... their emissions are heading in the same direction, they're flatlining," he told reporters.
"But the emissions increase is actually happening a lot of those countries, China included.
"And if the goal is to reduce emissions, then you obviously got to focus on the places which have the largest emissions."
Australia's emissions have increased over the past few years, while America's emissions have been trending downwards for a decade.
Meanwhile, youth climate activist Greta Thunberg lambasted world leaders in her address to the UN summit.
"You have stolen my dreams and my childhood with your empty words, and if you choose to fail us I say - we will never forgive you," she said.
"People are suffering. People are dying. Entire ecosystems are collapsing. We are at the beginning of a mass extinction - and all you can talk about is money and fairytales of eternal economic growth."