Russian businessman Anton Bakov says the struggle will continue to set up the Romanov Empire after last week's rejection by Kiribati.
The government turned down his investment plan under which he wanted to lease three uninhabited islands in the Line group and build resorts.
In a post on Facebook, Mr Bakov said difficulties were inevitable but they won't stop them.
Mr Bakov, who is the head of Russia's Monarchist Party and a former member of the Russian parliament, offered $US120 million to the government of Kiribati if it approved his plan.
He had hoped to use the islands to revive the Romanov Empire and create what he called an "alternative Russia".
Mr Bakov also said he planned to build a resort complex on Malden Island.