White House economic adviser Larry Kudlow has insisted Donald Trump is not backing off national security concerns, despite agreeing to allow US companies to sell some components to Chinese telecommunications giant Huawei.

Trump made the announcement on Saturday after meeting Chinese president Xi Jinping for trade talks at the G20 summit in Japan. Trump said US companies could make the sales if the transactions did not present a “great, national emergency problem”.

Several Republican senators expressed concerns. In a tweet, Marco Rubio of Florida called the decision a “catastrophic mistake”.

Lindsey Graham of South Carolina, a key ally of the president, told Face the Nation on CBS the agreement was “clearly a concession” and also said it would be a mistake if sales to Huawei involved “major technology”.

John Barrasso of Wyoming described the Chinese company as a clear threat to US national security.

“To me, Huawei in the United States would be like a Trojan horse ready to steal more information from us,” he told NBC’s Meet the Press.

Kudlow told Fox News Sunday and CBS Huawei would remain on an American black list as a potential security threat. He stressed that additional US licensing “will be for what we call general merchandise, not national security sensitive”, such as chips and software generally available around the world.

“What’s happening now is simply a loosening up for general merchandise,” Kudlow said. “This is not a general amnesty.”

US officials accuse Huawei of facilitating Chinese spying, a charge the company denies, and see it as a growing competitive threat to US tech companies.

Huawei’s founder, Ren Zhengfei, said earlier this month it has cut its projected sales by $30bn over the next two years due to curbs on access to American chips and other components. He said smartphone sales outside China will fall 40%.

Huawei’s US sales of network gear evaporated after a congressional panel labeled the company a security threat in 2012 and told phone carriers to avoid it. The Chinese company still has a patent portfolio it licenses to manufacturers and carriers.