WHO Director General Tedros Adhanom Ghebreyesus repeatedly called for unity and a halt to "politicization" of the global health crisis.
He said that he expected U.S. funding to continue with traditional bipartisan support.
The United States provided more than $400 million to the Geneva-based agency in 2019, according to U.S. figures.
The WHO website shows the United States as its top donor, contributing nearly 15% of the budget.
"We have kept the world informed about the latest data, information and evidence," Tedros said, noting that Thursday would mark 100 days since China first notified the organization of cases of "pneumonia with unknown cause" on December 31.
Tedros, a former foreign minister of Ethiopia, also rejected Trump's suggestion that the WHO was "China-centric," saying: "We are close to every nation, we are color-blind."