Malcolm Turnbull doubts North Korea's leader plans to "commit suicide" by launching a missile attack on the United States.
The prime minister was responding to Donald Trump's speech to the United Nations General Assembly during which he described Kim Jong-un as a "rocket man on a suicide mission".
"I do not think this guy will commit suicide," Mr Turnbull told Seven Network on Wednesday.
He said Mr Trump, who also vowed to "totally destroy" North Korea unless it backed down, was just stating the reality of the situation.
"It is very important that North Korea understands that if it attacks the US or its allies ... the United States will respond and respond in a way that would end the North Korean regime."
He described the situation as one of increasing gravity and risk and warned if there was a conflict many thousands of innocent people would die.
Foreign Minister Julie Bishop spoke with Mr Trump and US Ambassador to the UN Nikki Haley following his New York speech.
"We had a rather detailed discussion on what options are available to the international community and what is Kim Jong-un's end game," she said.
Asked about the strategic value of Mr Trump continually calling the North Korean leader "rocket man", Defence Minister Marise Payne told ABC radio: "The president is at the point where he is making his views entirely clear."
Senator Payne will be meet with US Defence Secretary James Mattis on Thursday to discuss the North Korea issues.
Labor leader Bill Shorten said it was time for all countries to work together and tone down the rhetoric.
"Cool heads and diplomatic language obviously are an important ingredient," he said in Melbourne.
The opposition leader and Labor foreign affairs spokeswoman Penny Wong will travel to South Korea and Japan on the weekend for talks with officials and to show Australia's solidarity with the two countries, which could wear the fall out of any North Korean attack.
