Armenia warned the international community of Turkish interference in its dispute with Azerbaijan after heavy fighting broke out over the breakaway Nagorny Karabakh region on Sunday.
"I call on the international community to use all existing levers to prevent Turkey's meddling which can once and for all destabilise the [Caucasus] region," Armenian Prime Minister Nikol Pashinyan said in a televised statement.
Turkey's "aggressive behaviour causes serious concerns", he said.
Armenia and Azerbaijan declared martial law amid fierce fighting involving tanks, aircraft and artillery. Both sides reported casualties while blaming each other for the latest clashes in their three-decade dispute over the region.
Turkish President Recep Tayyip Erdogan accused Armenia of attacking Azerbaijan, saying the country had "shown once again that it is the biggest threat to peace in the region".
Turkey calls on "the entire world to stand with Azerbaijan in their battle against invasion and cruelty", Mr Erdogan said after a phone call with Azeri President Ilham Aliyev.
He said Ankara's solidarity with Baku would "increasingly continue".
Russian President Vladimir Putin called for a de-escalation during a phone call with the Armenian prime minister, the Kremlin said.
"It is important to make every effort to prevent further escalation in the confrontation; more importantly, there must be an end to hostilities," Mr Putin said.
Later on Sunday, Turkish Foreign Minister Mevlut Cavusoglu said Turkey was talking to members of the Minsk group, which mediates between Armenia and Azerbaijan. Russia, France and the United States are co-presidents of the group.
The long-running conflict is a concern for western and regional countries in part because the South Caucasus serves as a corridor for pipelines transporting oil and gas to world markets.