The four islands, which have been in Russian hands since the end of World War II, have been a stumbling block to a formal peace treaty for the past 64 years. Medvedev said Japan has impeded progress recently by suggesting the islands, former Japanese territory, do not belong to Russia, reported Novosti, the Russian news agency.
The Soviet Union declared war on Japan in 1945 just before the Japanese government surrendered to the United States.
"We will proceed with dialogue to find a mutually acceptable solution to the peace treaty problem, however we cannot but notice attempts by our Japanese partners to doubt Russia's sovereignty of the Kuril Islands," Medvedev said.
He called cooperation between the two countries "an important factor in maintaining stability and security in the Asia-Pacific region."