"NATO's plans to hold exercises in Georgia ...are an open provocation. Exercises must not be held there where a war has been fought," Medvedev said.
He also warned that the exercises could have negative consequences for those who made the decision to hold them.
NATO says the Cooperative Longbow 09/Cooperative Lancer 09 command-and-staff exercises will not feature light or heavy weaponry. In response to Russian criticism, the Western military alliance has said the drills were planned before the Russia-Georgia conflict, and that the exercise is open to all ally states, including Russia.
Some 1,300 soldiers from 19 member-countries of the alliance and its partners are expected to participate.
"We view any actions that could be considered by Tbilisi as encouragement of a course towards the country's remilitarization and the senseless strengthening of military components as measures that run counter to the six principles of conflict settlement agreed last August," the Russian president said.
Earlier this week, Russian Foreign Minister Sergei Lavrov said it was "dangerous to appease the current Georgian regime, which has in no way abandoned attempts to solve its problems via militarization and the use of force."
A source at the NATO headquarters in Brussels told RIA Novosti that Russia is overreacting. He said the drills are "not the end of the world" and that "no one is being forced" to participate.
Moldova announced on Wednesday it was pulling out of the exercises in Georgia.