"China will not even be mentioned or discussed," Trump said in a post on Truth Social on Thursday about the meeting.
The New York Times did not immediately respond to a request for comment.
A U.S. official, speaking on condition of anonymity, told Reuters the briefing for Musk would be attended by senior U.S. military officials in the Pentagon and would be an overview on a number of different topics, including China.
Access to a closely guarded military plan would mark a sharp expansion of Musk's role as a Trump adviser who has spearheaded efforts to cut U.S. government spending.
It would also fuel questions about conflicts of interest for Musk, who as the head of Tesla and SpaceX has business interests in China and with the Pentagon.