Earlier almost 2,000 opposition supporters locked in a standoff with police in Yerevan ended their protest over February's alleged rigged elections following a call by Levon Ter-Petrosian, the opposition leader, to disperse.
Robert Kocharian, the Armenian president, declared a 20-day emergency over the weekend.
Police closed major streets as hundreds of helmeted servicemen wearing bulletproof vests and wielding assault rifles patrolled Yerevan, warning residents not to gather in groups.
The official results of the February 19 elections showed Ter-Petrosian finishing a distant second to Serzh Sarkisian, the prime minister.
The opposition leader, who is under house arrest, called on his supporters to go home and refrain from further protests during the emergency order, but vowed to continue efforts to force a new election once it expires.
"I do not want any victims and clashes between police and innocent people," Ter-Petrosian said. "That is why I am asking you to leave."
"We shall not retreat," the opposition leader said.
"Acting within the law, within the framework of the constitution, we shall struggle to the end, until the removal of this hateful and criminal regime, this bandit and kleptocratic regime."
On Friday Ter-Petrosian appealed to the constitutional court to overturn the results.
The opposition says Sarkisian stole the election by resorting to vote-buying, ballot stuffing and pressuring media to skew coverage in his favour, claims the government denies.
An envoy from the Organization for Security and Cooperation in Europe (OSCE), the leading regional security body, has offered to mediate in the conflict.
The US has urged both sides to exercise restraint.
Observers from the OSCE have said that the election had mostly met international standards, but that there were serious flaws especially in the counting of votes.