Washington wants its allies to ban Huawei, arguing the use of its kit creates the potential for espionage by China - a claim denied by Huawei and Beijing.
Robert Strayer, deputy assistant secretary for cyber, international communications and information policy at the U.S. State Department, said on a visit to Lisbon "There is no way to fully mitigate any type of risk except the use of trusted vendors from democratic countries."
"EU countries have no reason to use 5G mobile technology from Huawei because Sweden's Ericsson, Finland's Nokia and South Korea's Samsung are on par with the Chinese group in the field," the US official said.
The US stance has sparked tensions with allies like Prime Minister Boris Johnson, who has granted Huawei a limited role in building a 5G mobile network in Britain.
Huawei says it spent $15 billion last year on research to help it achieve market leadership. They claimed that no US company can offer the same range of technology at a competitive price.
Strayer told reporters that American companies like Dell, Cisco, Juniper and VMware "want to play a future role", seeing many European companies also getting involved.
The EU has said it would allow members to decide what part China's Huawei can play in 5G networks.
Last month, Portugal approved guidelines for its 5G strategy and launched a working group to permanently monitor the risks and security of this network.