"There are many countries that are not speaking, New Zealand isn't speaking either," he told reporters in Canberra on Friday.
"I wish them well for the summit, I'm sure it will be very nice."
This weekend's online Climate Action Summit has been organised by the United Nations, the UK and France, and is in lieu of a major climate meeting delayed until next year.
Leaders were asked to come to the table with stronger commitments to combat climate change, with Mr Morrison originally expecting to speak.
More than 70 nations are speaking at the event, including China, which has recently committed to net zero emissions by 2060.
Last week, Mr Morrison was looking forward to taking part and saw it as a chance to talk up Australia's achievements.
He was expected to announce Australia would no longer count past emissions reductions in order to calculate the Paris agreement target of a 26 to 28 per cent drop on 2005 levels by 2030.
No other country was planning to use the calculation method, and the UN is urging nation's to commit to net zero emissions by 2050.
Although Mr Morrison has flagged he will make the announcement regardless, climate is a sensitive policy area within his coalition parties and he has beefed up his language on the perceived credits.
"Those credits that have been earned have been earned by farmers investing in changes in their farming practices," he said.
The latest projections show Australia will beat the Paris goal if the prices of low-emissions technology reach targets outlined by the government.
One of those goals is for hydrogen to cost $2 per kilogram.
"If you can do that, then all of these (emissions reduction) targets take care of themselves," Mr Morrison said.
Without those prices, emissions will be 22 per cent below 2005 levels by 2030.
At face value that misses the Paris target mark, but the way progress on the goal is calculated uses an "emissions budget" approach and therefore projections show it will be met.
Greenpeace Australia says it's embarrassing the prime minister won't be speaking at the global summit.
"Scott Morrison has shown not one ounce of ambition to do anything to secure the future prosperity and security of Australia or the world in the face of the mounting climate threat," CEO David Ritter said in a statement.
Meanwhile, Mr Morrison will address a Pacific Islands Forum event on Friday evening on Australia's work on climate resilience and adaption.