Speaking in Hungary, the first stop in a five-nation European tour, Pompeo said the United States has an obligation to alert other governments to the risks of building networks with equipment from the Chinese telecommunications giant.
"What's imperative is that we share with them the things we know about the risks that Huawei's presence in their networks presents," he said. "Actual risks to their own people, to the loss of privacy protections for their own people, the risk that China will use this data in a way that is not in the best interest of Hungary."
If countries use Huawei equipment, "it makes it more difficult for us to partner alongside them," Pompeo said.
The Chinese government on Tuesday criticized Pompeo's remarks, accusing Washington of attempting to "sow discord between China and other countries."
The United States is "unscrupulously fabricating groundless accusations" and cracking down on the development of Chinese companies, Foreign Ministry spokeswoman Hua Chunying said at a regular media briefing. "These actions are unfair and immoral."
The US government has long been suspicious that Beijing could use Huawei equipment for spying but hasn't provided public evidence to support those concerns. There is particular concern about the security of 5G because it will be used to carry vast amounts of data that can connect robots, autonomous vehicles and other potentially sensitive devices.
"We would encourage all governments to take an objective look at the evidence and maintain an open, engaged approach to 5G," William Wu, the CEO of Huawei Technologies Hungary, said in a statement. "Excluding one supplier from technological developments in cyber security will damage technical and economic progress and harm competition."
Washington is trying to loosen that grip.
In the United Kingdom, Huawei is spending $2 billion on efforts to address government agencies' security concerns. Telecommunications operator BT (BT) said it would not buy Huawei equipment for the core of its 5G network but would continue to use it for other parts, such as mobile base stations.
Two close US allies outside Europe have already distanced themselves from Huawei. Australia and New Zealand restricted the company last year from providing equipment for 5G networks.
Canada is considering similar measures to restrict Huawei even as it walks a geopolitical tightrope between Washington and Beijing. Canadian police detained Huawei Chief Financial Officer Meng Wanzhou in December on behalf of US authorities. Meng is the daughter of Huawei founder Ren Zhengfei.