Nagorno-Karabakh declared independence from Azerbaijan nearly 30 years ago but it has not been recognised internationally, even by Armenia.
Armenian Prime Minister Nikol Pashinyan, who has fuelled outrage over a controversial peace deal with Azerbaijan, called Monday for a halt to violence after reports of an attempt on his life.
Last week, Pashinyan announced a Moscow-brokered peace deal that ended weeks of heavy fighting over the disputed region of Nagorno-Karabakh that left at least 2,400 dead and displaced tens of thousands.
Armenia agreed to cede parts of the region to Azerbaijan as well as other territories controlled by Armenian separatists since a 1990s post-Soviet war.
After the deal was announced, thousands of protesters took to the streets of the Armenian capital Yerevan, calling Pashinyan a “traitor” and demanding his resignation. Protesters also stormed government buildings.
On Monday, Pashinyan appealed for calm.
“Today I clearly stated that violence or the provoking of violence (especially armed violence) cannot in any way be a means of action for the government,” Pashinyan said on Facebook.
Pashinyan said he expected the opposition to also declare that it did not back “any violent action”.
Authorities on Saturday said they thwarted a plot to assassinate the prime minister and arrested opposition leader Artur Vanetsyan, the former head of Armenia’s security services.
Vanetsyan, leader of the centre-right “Homeland” party, was released on Sunday after a court ruled that his detention lacked legal grounds.
A dozen opposition leaders were detained last week for inciting riots but were also released by courts.
Clashes between Azerbaijan and Armenian separatists broke out in late September and persisted despite efforts by France, Russia and the United States to mediate ceasefires that collapsed as both sides accused the other of violations.