The Golden Globe- and Emmy Award-winning costume drama is produced by Carnival Films. It airs in the United Kingdom on ITV1 and in the United States on PBS.
PBS recently started selling baubles named for two of the early 20th century-set show's lead characters, Lady Mary Crawley and her sister, Lady Sybil.
The Daily Telegraph quoted a Carnival spokesman as saying Tuesday it did not sign off on the merchandise and is receiving no share of the profits from the sale of it.
"We did not authorize the sale of Lady Mary jewelry. Our lawyers have been in contact with PBS in order to remove these items from sale," the representative said.
Although the Telegraph said PBS has not publicly commented on the issue, the newspaper noted the television network has removed from its online shop references to Lady Mary and other characters from the series, which is now in its second season. ITV said recently it has ordered a third season of the show.