China's President Xi Jinping (centre R) and former US Secretary of State Henry Kissinger (centre L) walk to a meeting with delegates from the 2019 New Economy Forum at the Great Hall of the People in Beijing on November 22, 2019.

Henry Kissinger met in China with President Xi Jinping, and the details of his conversations were passed onto President Donald Trump, White House economic advisor Larry Kudlow told CNBC on Wednesday.

Kudlow, who has been a main presence in the Trump administration's efforts to craft a revamped trade deal with China, would not say whether the 96-year-old Kissinger is part of a back channel to Beijing or a separate track all together.

"Well, now you're getting into the family jewels and the price," Kudlow said.

Kudlow told CNBC that Kissinger, who served in senior roles under Presidents Richard Nixon and Gerald Ford, met with Xi "twice" during a weeklong trip to China, along with "other big shots."

During their talks, Xi said he would rather deal with Trump than Democrats "who won't talk about key trade issues, but instead will go on about human rights and other things," Kudlow said Kissinger told him.

"Now, let me be careful here," Kudlow quickly added. "President Trump made it very clear that we favor freedom and democracy and a peaceful solution in Hong Kong, and that we oppose, of course, the maltreatment of the Muslims and the Uighurs."

Kissinger delivered his message from Xi during a visit to the White House two weeks ago, Kudlow said. The economic advisor said he "promptly" wrote down Kissinger's dispatch and sent it to Trump.

A spokeswoman for Kissinger did not immediately respond to CNBC's request for comment on Kudlow's remarks.