The statement from a spokesman for US President Barack Obama highlighted concerns about the potential fallout from Trump's unusual call with Taiwan President Tsai Ing-wen on Friday, which prompted a diplomatic protest from Beijing on Saturday, Reuters reported.
White House spokesman Josh Earnest said senior National Security Council officials spoke twice with Chinese officials over the weekend to reassure them of Washington's commitment to the "One China" policy and to "reiterate and clarify the continued commitment of the United States to our longstanding China policy."
The policy has been in place for 40 years and is focused on promoting and preserving peace and stability in the strait separating China and Taiwan, which is in US interests, Earnest said.
"If the president-elect's team has a different aim, I'll leave it to them to describe," he said.
"The Chinese government in Beijing placed an enormous priority on this situation, and it’s a sensitive matter. Some of the progress that we have made in our relationship with China could be undermined by this issue flaring up," he said.
The call with Taipei was the first by a US president-elect or president with a Taiwan leader since then president Jimmy Carter switched diplomatic recognition to China from Taiwan in 1979, acknowledging Taiwan as part of "one China." China regards Taiwan as a renegade province.
Earlier on Monday, China's Foreign Ministry said Trump was clear about China's position on the Taiwan issue and that China had maintained contacts with his team.
Vice President-elect Mike Pence sought to play down the telephone conversation, saying on Sunday it was a "courtesy" call, not intended to show a shift in US policy on China.