"Just spoke to President XI JINPING of China concerning the latest provocative actions of North Korea," Trump tweeted. "Additional major sanctions will be imposed on North Korea today. This situation will be handled!"
In Washington, Secretary of State Rex Tillerson said a range of additional U.S. sanctions were being considered.
"We have a long list of additional, potential sanctions, some of which involve . . . financial institutions," he said when asked about possible measures as he posed for photos with the visiting Bahraini crown prince. "And the Treasury Department will be announcing those when they're ready to roll out."
On Wednesday, North Korea launched an intercontinental ballistic missile, its third and most advanced yet, with experts calculating that the U.S. capital is now technically within North Korean reach.
North Korea said the Hwasong-15 could be armed with a "super-large heavy nuclear warhead" and is capable of striking the entire U.S. mainland. In a government statement, it said Kim "declared with pride" that the country has achieved its goal of becoming a "rocket power."
In a statement, the White House said Trump "underscored the determination of the United States to defend ourselves and our allies from the growing threat posed by the North Korean regime" in his call with Xi.
"President Trump emphasized the need for China to use all available levers to convince North Korea to end its provocations and return to the path of denuclearization," said the statement.
According to China's state news agency Xinhua, Xi told Trump that denuclearization of the Korean Peninsula is "China's unswerving goal and China is ready to join the U.S. in pushing the nuclear issue toward a peaceful settlement."
After Trump visited China last month, he boasted of a promise from Xi "to use his great economic influence" over the North Korean regime to make it abandon its nuclear missile program. That promise is now being put to the test.
China has supported a stiff set of sanctions at the United Nations Security Council, but it remains North Korea's main trading partner and has been unwilling to take any drastic measures that might undermine the stability of the regime in Pyongyang, or change its strategic calculations.
Earlier on Wednesday, China's Foreign Ministry expressed its "grave concern and opposition" to the launch by North Korea, which it refers to by its official name, the Democratic People's Republic of Korea, or DPRK.
"We strongly urge the DPRK side to abide by the relevant U.N. Security Council resolutions and halt any moves that could aggravate the situation on the Korean Peninsula," Foreign Ministry spokesman Geng Shuang told a regular news conference.
But the question remains: How far is China prepared to push its neighbor and fellow Communist regime, at the behest of the United States and in the quest for a denuclearized Korean Peninsula?
Before the phone call between Trump and Xi, Chinese experts were skeptical that Beijing would go much further.
"If China imposes heavier sanctions, that would be symbolic at best I think," said Song Xiaojun, who used to run a government-linked military magazine. "China has a bottom line: 'Don't affect the life of the North Korean people, on humanitarian principles.' It gives them things like oil and food to allow people there to survive."
The latest missile test may not have come as a surprise in Beijing, since North Korea had already made it clear it was continuing with its missile test program, said Zhao Tong, a nuclear policy expert at the Carnegie-Tsinghua Center here.
But it will still underline Beijing's discomfort with its truculent neighbor and lead inevitably to further economic pressure, he said.
"The degree of further economic sanctions depends on North Korea's next step. For example will they launch a complete ICBM or take a more extreme step such as a nuclear test in the Pacific Ocean or atmosphere?" he said. "But the trend toward increasing the economic sanctions is going to continue."
Yet there are also signs that China may be tiring of the American approach of "maximum pressure."
In an editorial in its Chinese-language edition issued Wednesday, the nationalist Global Times newspaper said the test was a sign that past U.S. policy toward North Korea had failed and that the approach tried under Trump had also been unsuccessful.
The United States, it said, "despised Pyongyang" and as a result had ignored North Korea's security concerns and missed an opportunity to negotiate an end to the nuclear program — instead increasing pressure, raising tensions and narrowing the space for diplomacy since Trump took office.
And the state-run China Daily newspaper also issued an editorial that tried to shift the blame onto Trump for last week declaring North Korea a state-sponsor of terrorism, at a time when Pyongyang had briefly paused its missile testing program.
"It is vexed that a golden opportunity to build concerted momentum to encourage Pyongyang to engage in talks has been so casually wasted by the Trump administration's recent action of renaming Pyongyang a state sponsor of terrorism, which may have prompted Pyongyang's latest missile launch," it wrote. "There is a severe trust deficit among the relevant parties that is being exacerbated by the actions of Washington and Pyongyang."
That attempt to blame Washington rather than Pyongyang does not get much traction in the West, but it does reveal a mind-set among sections of the Communist Party.
"The United States has demanded that the Security Council hold an emergency meeting, but the leverage exerted by the international community on North Korea is almost exhausted," the Global Times wrote. "Now Pyongyang is extremely confident, for condemnation by the U.N. Security Council and possible new sanction measures are equal to a few more grains of dust on its body, or a few more drops of rain."
Yet there is no doubt that patience with Pyongyang is also in short supply in China right now. Lu Chao, a Korea expert at the Liaoning Academy of Social Sciences in Shenyang, called the latest test a "a very dangerous provocation."
"It will almost certainly provoke a U.S. reaction which will further destabilize the situation on the peninsula," he said, adding that North Korea was "going on its own."
"It's certain that, on issues regarding nuclear and missile tests, China opposes them but doesn't have much influence on North Korea," he said. "On the situation in the Korean Peninsula, China and North Korea lack effective communication."
There was a hint of an opening between Beijing and Pyongyang last month, experts say. North Korea refrained from conducting any missile tests during an important Communist Party Congress in November at which Xi was granted another five years in power.
A few days later, Xi sent a senior envoy, Song Tao, to brief the regime in Pyongyang about the party congress — although the envoy did not meet North Korean leader Kim.
Lu said the lack of a meeting might have been a sign that Kim was preparing to launch another missile. "If he met with Song Tao and then launched the missile, it would have infuriated China more," he said.
Since Trump's visit, China's Foreign Ministry announced that the main road connection with North Korea, the bridge across the Yalu River at the Chinese city of Dandong, would be temporarily closed while North Korea repairs the approach road on its side. A few days before that announcement, state-owned Air China also suspended flights between Beijing and Pyongyang, citing a lack of demand.
Those measures could be interpreted as signals to Pyongyang, but if they were, they were largely aimed at placating Washington rather than changing North Korea's strategic calculations, said Euan Graham, director of the International Security Program at the Lowy Institute in Sydney.
Shirley Feng, Liu Yang and Luna Lin in Beijing and Carol Morello in Washington contributed to this report.