"The following entities have been added to OFAC's SDN [specially designated nationals] List: MYANMAR TIMBER ENTERPRISE... MYANMAR PEARL ENTERPRISE," the Treasury Department said in a notice.
In a separate press release, the US Treasury said the companies are responsible for timber and pearl exports from Myanmar, which serve as key sources of government revenue for Myanmar's military.
The sanctions were authorised under US executive order 14014, which blocks property linked to the coup in Myanmar.
On 1 February, the Myanmar military overthrew the civilian government and declared a year-long state of emergency. The coup triggered mass protests and was met by deadly violence, resulting in the death of several hundred people.