He said Chinese officials "ignored" their reporting obligations to the WHO and pressured the organisation to mislead the world when the virus was first discovered, reports AP.
Trump said the US contributes about $450 million to the world body while China provides about $40 million.
The US is the largest source of financial support to the WHO and its exit is expected to significantly weaken the organisation. Trump said the US would be "redirecting" the money to "other worldwide and deserving urgent global public health needs," without providing specifics.
The Trump administration may soon expel thousands of Chinese graduate students enrolled at US universities and impose other sanctions against Chinese officials in the latest signs of tensions between Washington and Beijing that are raging over trade, the coronavirus pandemic, human rights and the status of Hong Kong.
President Trump said he would make an announcement about China on Friday, and administration officials said he is considering a months-old proposal to revoke the visas of students affiliated with educational institutions in China linked to the People's Liberation Army or Chinese intelligence.
Trump is also weighing targeted travel and financial sanctions against Chinese officials for actions in Hong Kong, according to the officials, who were not authorised to discuss the matter publicly and spoke on condition of anonymity.
"We'll be announcing what we're doing tomorrow with respect to China and we are not happy with China," Trump told reporters at an unrelated event Thursday, referring mainly to COVID-19. "We are not happy with what's happened. All over the world people are suffering, 186 countries. All over the world they're suffering. We're not happy."
The proposal to revoke the visas is not directly related to the dispute over Hong Kong, nor is it tied to US criticism of China for its handling of the coronavirus outbreak. Rather, it is connected to various elements of trade and human rights issues that have seen US officials complain about Chinese industrial espionage and spying and harassment of dissidents and religious and ethnic minorities.
But the timing of a potential announcement could come at a time of increasingly heated rhetoric about the imposition of national security laws on Hong Kong in violation of the Sino-British accord.
The US hosted 133,396 graduate students from China in the 2018-19 academic year, and they made up 36.1 percent of all international graduate students, according to the Institute of International Education. Overall, there were 369,548 students from China, accounting for 33.7 percent of international students who contributed nearly $15 billion to the US economy in 2018.
The proposal first began to be discussed last year when the administration moved to require Chinese diplomats based in the United States to report their domestic US travel and meetings with American scientists and academics. At the time, US officials said it was a reciprocal measure to match restrictions that American diplomats face in China.
Those limits were followed by a requirement that Chinese state-run media in the US register as "foreign diplomatic missions" and report their property holdings and employee rosters to the government. That was, in turn, followed by the limiting of the number of visas for Chinese journalists allowed to work in the United States.
China retaliated for the visa limitations by expelling several reporters from US media outlets, including The Washington Post and The New York Times.