"Mark McGowan's comments yesterday were sad ... give it up, mate," Mr Littleproud told the Nine Network on Tuesday.
The deputy Nationals leader, who worked with Mr Dutton in the defeated Morrison government, came to his coalition colleague's aid after Mr McGowan delivered a scathing assessment of the former defence minister.
The premier said an "extremely conservative" Mr Dutton did not fit with modern Australia,
"I actually don't think he's that smart," he said.
But Mr Littleproud said Mr Dutton provided the balance Australians were looking for in a federal leader.
"On economic and national security he is quite hard ... (but) he is more pragmatic on some of the more social and environment issues than people think," he said.
Acting Prime Minister Richard Marles believes Mr McGowan always has "wise things to say".Â
"I think the point here is ... what we saw from the Liberals was an attempt to create division where it didn't exist, and that diminished the national interest," he told Sky News.
The federal Liberal party needs a new leader after defeated prime minister Scott Morrison resigned after the weekend's election loss to Labor.