The World Health Organization's top official said Monday that partisan politics and lack of global solidarity are helping to fuel the coronavirus pandemic.

He urged countries to work together as Covid-19 continues to spread throughout the world.

"The cracks between people and the cracks between parties is fueling it," WHO Director-General Dr. Tedros Adhanom Ghebreyesus said. "Don't use this virus as an opportunity to fight against each other or score political points. It's dangerous. It's like playing with fire."

Without global solidarity, the worst of the pandemic is still "ahead of us," Tedros said during a press conference at the agency's Geneva headquarters. The Ethiopian microbiologist previously said he has received death threats and racist insults.

"This virus is dangerous. It exploits cracks between us," he said. "We need global solidarity that's cemented on genuine national unity. Without national unity and global solidarity, trust us, the worst is yet ahead of us. Let's prevent this tragedy."

The virus, which emerged in Wuhan, China over three months ago, has infected more than 2.4 million people worldwide and killed at least 165,000 as of Monday, according to data from Johns Hopkins University. However, infectious disease experts say the number of those who have had the virus is likely much higher as people go undetected and countries struggle with testing.

Tedros' comment came six days after President Donald Trump announced that the U.S. will suspend funding to WHO while it reviews the agency's response to the Covid-19 pandemic. Trump criticized the international agency's response to the outbreak, saying "one of the most dangerous and costly decisions from the WHO was its disastrous decision" to oppose travel restrictions.

The WHO said it would turn to other countries to help fill any gaps in financing its Covid-19 response work, expressing "regret" for Trump's decision.

The U.S. agency's funding runs in two-year budget cycles. For the 2018 and 2019 funding cycle, the U.S. paid a $237 million required assessment as well as an additional $656 million in voluntary contributions, averaging $446 million a year and representing about 14.67% of its total budget, according to spokesman Tarik Jasarevic.

Tedros said Monday the agency had warned developed countries the virus would "surprise" them.

"It did. We said that," he said. "Let's stop additional surprises."

"Please work together. We need national unity. We've seen the tragedy and we need global solidarity that's based on honest and genuine national unity," he added.

— CNBC's Jasmine Kim contributed to this article.