China, Pyongyang's main economic and diplomatic ally, opposes any military intervention and calls for a resolution through dialogue.
US President Donald Trump warned on Saturday that he would "no longer" allow China to "do nothing" on North Korea, after the belligerent hermit state launched an intercontinental ballistic missile test.
In his critique, which came in two tweets, Trump linked trade woes with the Asian giant to policy on North Korea, after South Korea indicated it was speeding the deployment of a US missile defense that has infuriated China.
"I am very disappointed in China. Our foolish past leaders have allowed them to make hundreds of billions of dollars a year in trade, yet they do nothing for us with North Korea, just talk," Trump wrote.
Trump has vowed to take "all necessary steps to ensure the security of the American homeland and protect our allies in the region."
The US and South Korea conducted a live-fire exercise using surface-to-surface missiles after the launch, the US army said.
The heads of the US and South Korean militaries discussed "military response options" after North Korea's launch, the Pentagon said.
The US military will also roll out "strategic assets" to the South following the North's missile test late Friday, according to South Korean defense minister Song Young-Moo.
Song declined to specify the nature of the mobilization, but the phrase usually refers to high-profile weapons systems, such as stealth bombers and aircraft carriers.
The THAAD battery comprises six interceptor missile launchers. Two launchers have been tentatively deployed at a golf course-turned-US military base in Seongju County, 187.5 miles (300 kilometres) south of Seoul.
China has long argued the deployment will destabilise the region.
On trade, the United States has blamed the unbalanced relationship — marked by a trade deficit with China of $309 billion last year — on Beijing's policies that impede access to their market.
China says Washington's own rules restricting US high-tech exports are partially to blame.