"The task is not easy, it's clear it will only be solved by long, painstaking and creative work," Lavrov told journalists following his meeting with Japanese counterpart Taro Kono.
"Solving a problem that remains unresolved more than 70 years on from the end of the war is not easy," Kono said at a joint press conference, in remarks translated into Russian.
"It cannot be said that as a result of today's talks we were able to overcome these differences."
Tokyo has refused to recognise Moscow's sovereignty over the islands, preventing the two countries from signing a peace treaty formally ending hostilities.
But both face domestic opposition to any compromise and at a meeting in Moscow in January fell short of reaching an agreement.
A further meeting between the foreign and defence ministers of the countries will take place at the end of May in Tokyo, Lavrov said Friday.
Moscow has said negotiations should be based on a 1956 Soviet-Japanese declaration which calls for the signing of a peace accord before the possible handover of two of the smaller islands to Japan.
But giving away even uninhabited islands would be poorly received in Russia, where World War II is hugely symbolic and post-war territorial gains are seen as non-negotiable.
Moscow in recent months has taken further steps to consolidate its hold on the islands, which are home to some 20,000 people.
In February it said it had laid fibre-optic cables to provide homes and businesses there with high-speed internet access.
(This story has not been edited by Business Standard staff and is auto-generated from a syndicated feed.)