The order signed by Trump prohibits purchase or use of equipment from companies that pose "an unacceptable risk to the national security of the United States or the security and safety of United States persons."
The White House said no particular country or company was targeted, only those controlled by "a foreign adversary."
"There are enormous threats that could be posed by these types of technologies," said a senior White House official, speaking on condition of anonymity.
However, the measure is widely seen as being prompted by already stated concerns over an alleged spying threat from Huawei.
US officials have been trying to persuade allies not to allow China a role in building next-generation 5G networks, warning that doing so would result in restrictions on sharing of information with the United States.
The United States has already banned its government agencies from buying equipment from Huawei, a rapidly expanding leader in 5G technology, over fears Beijing could spy on communications and gain access to critical infrastructure.
China's government, which is already in a protracted trade war with the United States, is furious about the push back against Huawei.
"For some time, the United States has abused its national power to deliberately discredit and suppress by any means specific Chinese enterprises, which is neither honourable nor fair," foreign ministry spokesman Geng Shuang said.
"We urge the US side to stop the unreasonable suppression of Chinese enterprises on the pretext of national security and to provide a fair and non-discriminatory environment," the spokesman said.
Earlier, David Wang, executive director of Huawei's board, shrugged off news of the upcoming emergency declaration.
"Our business in the US is not very big. We are a company with global operations, so if there is this or that change in any country, the impact on our global business is very little," he said. (AFP)