WASHINGTON (Reuters) -Trade Representative Jamison Greer said on Sunday that the U.S. reached out to China for a phone call following an announcement that it was expanding its rare earths export controls but Beijing deferred, while China accused the U.S. of what it called "double standards."

"I can tell you that we were not notified, and quickly, as soon as we found out from public sources, we reached out to the Chinese to have a phone call, and they deferred," Greer told Fox News' "Sunday Briefing," while calling China's move "a power grab."

U.S. President Donald Trump responded on Friday to China's expansion by imposing 100% tariffs on China's U.S.-bound exports, along with new export controls on "any and all critical software" by November 1.

"Highly respected President Xi just had a bad moment. He doesn't want Depression for his country, and neither do I. The U.S.A. wants to help China, not hurt it," Trump wrote on Truth Social on Sunday.

The Chinese embassy in Washington, D.C., did not immediately return a request for comment.

China hit out at Trump's latest tariffs on Chinese goods, accusing the U.S. on Sunday of what it called "double standards."

In a report by state broadcaster CCTV, the Chinese commerce ministry defended its curbs on exports of rare earth elements and equipment, but stopped short of imposing new levies on U.S. products. It said the restrictions are driven by concern over the military applications of these elements at a time of "frequent military conflicts."

Beijing also pointed out the U.S. added Chinese companies to a trade blacklist and levied port fees on China-linked ships as examples.

China and the U.S. have been embroiled in a trade war since Trump returned to the White House earlier this year. Global financial markets tumbled as Trump floated the possibility of canceling an upcoming meeting with Chinese President Xi Jinping.

Greer said he believes that markets will calm in the coming week as things settle. He said a Trump-Xi meeting on the sidelines of the Asia-Pacific Economic Cooperation forum in South Korea could still happen later this month.