Senator Canavan told ABC News on Tuesday, "net zero is dead anyway".
But Mr McCormack said the National Party was committed to the net-zero emissions target they agreed to.
"Nats are country people and when country people look you in the eye and shake your hand and say, 'that's a deal', then it's a deal," he told ABC Radio National on Wednesday.
"It doesn't help (election chances). ... (Canavan) needs to be talking about the good things that we've done ... many of the programs that I put in place when I was the deputy prime minister, that's what he needs to be talking about."
Treasurer Josh Frydenberg said Senator Canavan's position was "old news" and the Liberal-National coalition remained committed to the target.
"Net zero is a commitment by the coalition that is clear, that is firm and that is non-negotiable," he told the Nine Network on Wednesday.
"(Matt Canavan) has held that position for some time, but it's not the position of his party, it's not the position of my party, and it's not the position of the coalition."
Labor's climate spokesman Chris Bowen said the coalition was still arguing over the basics when it comes to action on climate change.
"These climate deniers and delayers will continue to be a handbrake on real action on climate after nine years in office," he told ABC Radio National.
Senator Canavan's comments come as the coalition continues to claim the opposition will introduce a carbon tax if elected, which Labor has ruled out.
Opposition Leader Anthony Albanese said on Tuesday there would be no carbon tax ever under his government.
Mr Bowen said the coalition was engaged in a "lazy, toxic, scare campaign" on the issue.
"Scott Morrison will continue to engage in that lazy, toxic, scare campaign because he's not really committed to climate change, he prefers ... to lie about the economic impacts of (Labor) policy," he said.
"If you're misleading voters depending on their preferences on climate then you can't be taken seriously."