The broadcaster was first alerted to the social media page advertising “David Attenborough CBD Oil” by one of his supporters, who wrote to him after she was “misled by the adverts” and overcharged for the product.
CBD – short for Cannabidiol – is an oil derived from the cannabis plant, which can be used for medicinal purposes to relieve symptoms.
His spokesman said Sir David does not have an authorised Facebook account and the offending page has been reported.
In a statement, he said: “Sir David Attenborough has been appalled to discover companies are using his name and image to advertise CBD oil on Facebook and elsewhere online.
“These are not genuine endorsements and Sir David has had no involvement whatsoever with these products.
“The companies do not have permission to use Sir David’s name or image – Sir David only allows the use of his name and image for marketing in connection with his own programmes and books.”
The spokesman added: “He only discovered the existence of such adverts, including the Facebook page, when he was alerted to them by a supporter who wrote to him after she had been misled by the adverts and had been overcharged by the suppliers.
“He wishes to extend his sympathies to anyone that has been adversely affected by these companies and their actions.
“He also wants to make it clear that there is no authorised David Attenborough Facebook account, as there are many false accounts on Facebook claiming to be his.
“This is being reported to Facebook and Sir David would encourage anyone who spots these fraudulent adverts also to report them to Facebook.”
The TV presenter, 94, joined Instagram in September, using his debut post to upload a video warning followers that “saving our planet is now a communications challenge”.
He added: “I am making this move and exploring this new way of communication to me because, as we all know, the world is in trouble.”