Georgia has sent a military force to the volatile Kodori gorge in the breakaway Abkhazia region, prompting a warning from Russia.
The foreign ministry said Georgia had failed to tell Russian peacekeepers or UN observers about the deployment.
"We call on the Georgian side to refrain from taking military action," said the Russian statement, quoted by the Interfax news agency.
A militia leader, Emzar Kvitsiani, is based in the gorge, defying Georgia.
Russia put its troops in the area on alert and condemned the Georgian deployment as a "serious violation of the 1994 Moscow ceasefire agreement", which halted fighting between Georgian and Abkhaz separatist forces.
The separatist Abkhaz government also protested against the deployment of Georgian troops to the strategically important valley.
Georgia has demanded that Russia withdraw its troops from Abkhazia and another breakaway region - South Ossetia.
Moscow insists that its troops are peacekeepers, needed to prevent a resumption of hostilities.
Abkhaz rebels drove Georgian troops from the region in 1993.