Russia's Foreign Ministry has expressed "serious concern" in light of a recent flare-up of violence in the disputed Armenian enclave of Nagorno-Karabakh in Azerbaijan.
"We see the events of recent days as serious violations of a cease-fire agreement and of declared intentions to achieve regulation through political means," spokeswoman Maria Zakharova said in a statement on Saturday.
"We take the position that any further escalation is unacceptable," it said.
The Organization for Security and Cooperation in Europe (OSCE) issued a statement on Saturday warning against further escalation.
"Retaliation and further violence will only make it more difficult to continue efforts to bring about a lasting peace," the OSCE head and the co-chairs of the OSCE Minsk group said in a statement on Saturday.
The clashes have already claimed at least 15 lives in an area that has been the site of a frozen conflict even since a cease-fire was reached 20 years ago following a war that claimed 30,000 lives.
Azerbaijan and Armenia have repeatedly accused each other of escalating the situation.
Nagorno-Karabakh, which has a mostly Armenian population, runs its own affairs, but enjoys significant military and financial support from Armenia.
Russia, France and the U.S. spearheaded international efforts to reach a permanent settlement of the conflict, so far unsuccessfully. In September, Armenia decided to join the Russia-led Customs Union.
Material from Reuters was used in this report.