Bill Shorten has counselled one of his senators after she accused the government of using the threat of homegrown terrorism to deflect attention from its unpopular budget.

The Labor leader’s rebuke came after the immigration minister, Scott Morrison, labelled Sue Lines a “muppet” for her comments.

Lines said the government’s “Team Australia” rhetoric on national security issues during parliament this week was just “a shield to try and deflect from the awful mess they’re in with their budget”.

Morrison, who sits on the cabinet’s national security committee, said the senator’s comments were disappointing.

“If she doesn’t believe that the IS [Islamic State] involvement in Iraq and Syria presents a genuine and real threat to Australia then she’s a muppet,” he told ABC radio.

“She should be hauled into line by her leader and return the debate to the adults.”

Shorten said he had spoken with Lines about the comments but would not go into details of the conversation.

“I and Labor recognise that national security is a matter which goes above day-to-day politics,” he said.

Other Labor figures also distanced themselves from Lines’s comments.

Shorten’s parliamentary secretary, Jim Chalmers, said serious issues such as terrorism should be above politics.

The Labor frontbencher Kate Ellis said her colleague was entitled to her opinion, although “I certainly wouldn’t have voiced it in that manner”, she said.