Russia fought a five-day war with Georgia last August after Georgian forces attacked South Ossetia in a bid to bring it back under central control. A total of 64 Russian soldiers were killed during the period, including 10 peacekeepers.
"The dramatic events in South Ossetia clearly showed that... the fire of a real war can break out from a local conflict even nowadays," Medvedev said at a soiree devoted to Fatherland Defenders' Day, due on Monday.
"We stopped the aggressor. We defended the lives of people and prevented a humanitarian disaster," he said. "To prevent similar events in the future, the international community needs... to work out new, really reliable approaches to ensuring international security."
Russia recognized Abkhazia and South Ossetia as independent states two weeks after the end of the war with Georgia. Nicaragua has so far been the only other country to recognize the republics.
Both South Ossetia and Abkhazia split from Georgia amid bloody post-Soviet conflicts. The majority of residents of both republics have had Russian citizenship for many years.