The operator has appealed the decision, however, ensuring it will not be implemented until the appeal is finalised; Kindred believes the decision has "no legal basis."
Lottstift ruled Trannel International sites Unibet, Maria Casino, Grand Piano and Bingo.com have all offered illegal gaming in Norway.
The regulator says gambling is not allowed in the European nation without its express permission.
Lottstift had sent letters to Trannel International in February, followed by an additional notification in April.
When contacted for comment by Gambling Insider, Kindred said: "We have received the Gaming Authority's decision and believe there is no legal basis for making such a decision: a decision that concludes activities operated in another EU country, where one is authorised to operate, is illegal and goes far beyond the jurisdiction of the Gaming Authority.
"Norway does not have the authority to intervene against activities lawfully operated in other countries. We therefore oppose the conclusions of the decision and will appeal this.
"Kindred Group is a company regulated internationally and is licensed to offer gambling. It is not illegal for Norwegians to play games licensed from another country. The Norwegian Gaming Authority does not have the jurisdiction to intervene against foreign operations even if one chooses to accept Norwegian customers."
