A Facebook spokeswoman said the new policy arose from the company's review of its rules following its recent efforts to encourage new forms of commerce on the site.
Facebook expanded its digital payments service last summer, allowing users of its Messenger service to send electronic payments to other individual users.
"Over the last two years, more and more people have been using Facebook to discover products and to buy and sell things to one another," Monika Bickert, who oversees Facebook product policies, said.
"We are continuing to develop, test, and launch new products to make this experience even better for people and are updating our regulated goods policies to reflect this evolution."
