Trump has been engaged all week in a war of words with the North over its weapons and missile programs, as US media reported Pyongyang has successfully miniaturized a nuclear warhead.
The Republican billionaire has progressively ramped up the tone throughout the week -- after brandishing a threat of unleashing "fire and fury" on Pyongyang, he said Thursday maybe that statement "wasn't tough enough."
The North's official KCNA news service countered in an editorial that "Trump is driving the situation on the Korean peninsula to the brink of a nuclear war," calling the US "the heinous nuclear war fanatic."
The saber-rattling has intensified daily, sparking worldwide concerns that a miscalculation by either side could trigger a catastrophic conflict on the Korean peninsula.
China, Russia and Germany have urged both sides to tone down the rhetoric.
"Military solutions are now fully in place, locked and loaded, should North Korea act unwisely. Hopefully Kim Jong Un will find another path!" Trump wrote Friday from his golf club retreat in New Jersey, where he is on a working vacation.
Later in the day, he lashed out at Pyongyang's plans to launch missiles towards the US Pacific territory of Guam, urging Kim to heed his warnings.
"I hope that they are going to fully understand the gravity of what I said, and what I said is what I mean," Trump told reporters.
"If he does anything with respect to Guam or anyplace else that's an American territory or an American ally, he will truly regret it, and he will regret it fast."
China -- Pyongyang's main diplomatic ally -- urged Trump and Kim to avoid any further escalation.
"We call on the relevant parties to be cautious with their words and actions, and contribute more toward easing tensions and enhancing mutual trust," Chinese foreign ministry spokesman Geng Shuang said in a statement.
Beijing has repeatedly pushed resuming long-dormant six-party talks to peacefully resolve the mounting tensions, but its position has been overshadowed by Trump and Kim's emerging game of brinkmanship.
Trump has called on China to "do a lot more" to heap pressure on Kim.
Russia's Foreign Minister Sergei Lavrov said Moscow was "very alarmed" at Trump's tough talk, and said Washington should take the first step toward cooling tensions.
"When a fight has nearly broken out, the first step away from the dangerous threshold should be taken by the side that is stronger and smarter," Lavrov said.
German Chancellor Angela Merkel joined the intensifying chorus of calls for restraint, saying diplomacy was the answer.
Nearly a week ago, the UN Security Council unanimously passed fresh sanctions against Pyongyang over its weapons program, including export bans, a new punishment that could cost North Korea $1 billion a year.
"This is clearly a time for all the parties to focus on how to de-escalate and lower the tensions," said the spokesman for United Nations Secretary General Antonio Guterres, Stephane Dujarric.
Tensions on the Korean peninsula tend to increase when Seoul and Washington launch major military joint exercises, and the next, Ulchi Freedom Guardian, is set to kick off around August 21.
'Tragedy of war'
US Defense Secretary Jim Mattis appeared intent Thursday on easing the tension, describing the prospect of war as "catastrophic" and saying diplomacy remained the priority.
Asked Friday if Mattis was aware of Trump's latest tweet, spokesman Colonel Rob Manning simply said the Pentagon chief was "in close and constant contact with the president."
A White House official noted: "There are military plans for just about any crisis we may face in the world. (...) This isn't anything new."
In China, the state-run Global Times said Friday that Beijing should "stay neutral" and not intervene on Pyongyang's side if it triggered a conflict.
Meanwhile in South Korea, calls mounted for Seoul to develop atomic weapons of its own, with the Korea Herald saying in an editorial: "Now is time to start reviewing nuclear armament."
'Bereft of reason'
Relations between Washington and Pyongyang have been tense for months, in the wake of the North's repeated missile tests, including two successful intercontinental ballistic missile (ICBM) test launches in July that are believed to have brought much of the US mainland within range.
North Korea raised hackles in the United States when it announced a detailed plan to send four missiles over Japan and towards Guam, an island territory of some 165,000 people, where some 6,000 US soldiers are based.
Pyongyang said the scheme to target the island, a key US military outpost in the western Pacific, was intended to "signal a crucial warning" as "only absolute force" would have an effect on a US leader "bereft of reason."
The tough talk caused global markets to plunge this week, with stocks in the red again Friday in Asia and much of Europe.
(This story has not been edited by NDTV staff and is auto-generated from a syndicated feed.)