The WHO chief Tedros Adhanom Ghebreyesus made the remarks after Trump scrutinized the UN body’s initial response to the contagion, and threatened to pull US funding for the organization.
"Please don't politicize this virus. It exploits the differences you have at the national level. If you want to be exploited and if you want to have many more body bags, then you do it. If you don't want many more body bags, then you refrain from politicizing it. My short message is: Please quarantine politicizing Covid. The unity of your country will be very important to defeat this dangerous virus," Tedros said at a news conference in Geneva, Switzerland.
Tedros called for unity and a halt to "politicization" of the global health crisis, urging the United States to show "honest leadership".
United Nations Secretary General Antonio Guterres also said it was not the time to criticize the early response to the outbreak.
"Now is the time for unity, for the international community to work together in solidarity to stop this virus and its shattering consequences," Guterres said in a statement.
Trump, whose own response to the corona crisis has been widely criticized, claimed the WHO had downplayed the coronavirus, and threatened to freeze the organization funding, only to later backtrack from the threat.
The US president accused the WHO of favoring China, while taking US money.
"I can't believe he (Tedros) is talking about politics when you look at the relationship they have to China. So China spends 42 million, we spent 450 million and everything seems to be China's way. That's not right, it's not fair to us and honestly it's not fair to the world," Trump said.
The WHO chief rejected Trump's suggestion that the UN body was "China-centric", saying: "We are close to every nation, we are color-blind."
Tedros urged the United States to join with China in combating the pandemic rather than indulging in a blame game.
"The United States and China should come together and fight this dangerous enemy. The focus of all political parties should be to save their people," he said.
"If you don't want many more body bags, then you refrain from politicizing it. It's like playing with fire," Tedros added.
Tedros noted that Thursday would mark 100 days since China first notified the organization of cases of "pneumonia with unknown cause" on December 31.
The coronavirus has killed more than 80,000 people worldwide, while more than 1.4 million people have tested positive.