He said: "We are with you a thousand percent".
The tough talk capped a week in which long-standing tensions between the countries risked abruptly boiling over.
There has been an ongoing tension in the region since North Korea has staged two nuclear bomb tests a year ago and launched two intercontinental ballistic missile tests (ICBM) in July in defiance of world powers.
While tourists are free to visit the secretive state as part of strictly controlled tour groups, they are told to never take photos of soldiers by their handlers.
China "will stay neutral" if North Korea launches missiles threatening the United States, according to an op-ed in the influential Chinese newspaper Global Times. They weren't authorized to discuss the confidential exchanges and spoke on condition of anonymity.
Trump on Friday sought to project military strength, only dialing back slightly throughout the day.
Trump kept up the tough rhetoric on Friday, warning Pyongyang would "truly regret" taking any hostile action against the United States after he tweeted that the USA military was "locked and loaded". Pacific territory of Guam. Such declarations, however, don't indicate a new, more aggressive posture.
"China opposes both nuclear proliferation and war in the Korean Peninsula".
Russian Federation and Germany have also urged both sides to tone down the rhetoric.
Russian Foreign Minister Sergei Lavrov said Friday that "the risks are very high" that the United States and North Korea could go to war, while German Chancellor Angela Merkel said an escalation in language was "the wrong response". She called on the U.N. Security Council to continue to address the crisis.
German Chancellor Angela Merkel said there was no military solution, and "an escalation of the rhetoric is the wrong answer". "Perhaps she is referring to Germany".
Calvo responded by saying he feels safe and confident with Trump's leadership: "I'm glad you're holding the helm, sir".
The new punishment could cost North Korea $1 billion a year, and even China voted for the US-drafted proposal.
It added the relationship between Trump and Xi was "extremely close" and "will hopefully lead to a peaceful resolution of the North Korea problem".
Trump also met with his national security team and told reporters he's still hoping for a "peaceful solution".
Meanwhile, China, North Korea's most important ally and trading partner, has reiterated calls for calm.
They are expected to cut North Korea's export revenues by one third.
Mr Calvo agreed with the President that Guam is "paradise".