Military strikes not first choice, but won't put up with North Korea: Trump

US President Donald Trump said on Wednesday that military action was not the "first choice" of his administration on the Korean Peninsula nuclear issue.

On his way to participate in a tax reform event, Trump told reporters that military action against North Korea was "not the first choice, but we will see what happens", Xinhua news agency reported.

His latest comments were less harsh than ones he made last month where he threatened "fire and fury" against the Pyongyang regime.

The US has urged China, which is the North's main trading partner, to put more pressure on the reclusive nation to limit his controversial missile programme.

Trump said he has had a "strong" and "frank" conversation with Xi Jinping about North Korea.

"I believe that President Xi agrees with me 100 per cent. He doesn't want to see what's happening there, either," Trump told reporters.

"President Xi would like to do something. We'll see whether or not he can do it. But we will not be putting up with what's happening in North Korea," Trump said.

Trump's comments came during his telephonic conversation with his Chinese counterpart Xi Jinping to discuss the situation in the Korean Peninsula after North Korea carried out its sixth and most powerful nuclear test to date.

The Chinese president said the general direction should head toward a peaceful settlement of the issue, adding that dialogue combined with a set of comprehensive measures is best for seeking a long-term solution.

Xi said China had been adamant in preserving international nuclear non-proliferation, maintaining peace and stability on the peninsula, and resolving the nuclear issue through talks, China's state-run Xinhua news agency reported.

In a related development, the White House said on Wednesday that Trump spoke with British and Australian leaders by phone regarding the nuclear issue on the Korean Peninsula.

The White House said that in his discussion with British Prime Minister Theresa May on Tuesday, Trump stressed that now is not the time to talk to North Korea, and made clear that all options remain open to defend the US and its allies.

Speaking with Australia's Prime Minister Malcolm Turnbull, the leaders confirmed that their two countries will intensify joint efforts to denuclearize the DPRK, said a statement by the White House.

North Korea on Sunday detonated a hydrogen bomb that can be carried by an intercontinental ballistic missile (ICBM), North Korea's Central Television announced. North Korea's nuclear testing and launches using ballistic missile technology have violated UN Security Council resolutions.

China's permanent representative to the UN Liu Jieyi on Monday condemned the latest nuclear test by North Korea and urged the country to return to the track of dialogue. China will not allow chaos and war on the Korean Peninsula, he said.

Liu said the suspension-for-suspension proposal and dual-track approach put forward by China together with the Russian proposal of a step-by-step approach is a realistic and feasible roadmap for the settlement of the issue.