A group of Armenian protesters barged into a government building in the capital chanting for Prime Minister Nikol Pashinyan to quit, ahead of rival street rallies expected later on Monday, the RIA news agency reported.
Mr Pashinyan, in power since 2018 in the ex-Soviet republic of less than 3 million people, is facing a crisis after the army last week demanded he step down, prompting him to decry a coup attempt and sack the army's top general.
But the president refused to sign off on the general's removal on Saturday, declaring it unconstitutional.
Mr Pashinyan has sent back his decree demanding the general's dismissal to the president's office.
The country's Security Council on Monday urged President Armen Sarkissian to approve the sacking, the Interfax news agency reported. RIA reported that Mr Pashinyan also met Mr Sarkissian on Monday.
Mr Pashinyan's followers plan to rally in his support at 1430 GMT on a central square in Yerevan. Thirty minutes before that, his opponents plan to hold a rival protest next to parliament calling for his downfall on a separate square.
Mr Pashinyan has faced calls to resign since last November when he agreed to a Russian-brokered ceasefire that halted six weeks of fighting between ethnic Armenian and Azeri forces over the region of Nagorno-Karabakh.
His critics accuse him of bungling the conflict in which Azerbaijan made territorial gains in and around Nagorno-Karabakh, an enclave internationally recognised as part of Azerbaijan but populated and until recently fully controlled by ethnic Armenians.
Mr Pashinyan has accepted responsibility for the conflict's outcome but rejected calls to resign.
He defended the peace deal as a painful but necessary move to prevent Azerbaijan from overrunning the entire Nagorno-Karabakh region. The fighting with Azerbaijan that erupted in late September and lasted 44 days has left more than 6,000 people dead. Russia has deployed about 2,000 peacekeepers to monitor the November 10 peace deal.
Watch: Prime Minister Nikol Pashinyan blasts the military after 'coup attempt'
Armenia's prime minister blasts the military after 'coup attempt'
