Immediately after his hour-long speech the protesters marched to the intersection of three avenues forming Yerevan's sprawling France Square and blocked traffic through it. Pashinian urged them to stay there through the night, saying that riot police will not attempt to disperse them in that case. One of its main platforms was criticizing constitutional changes approved following a December 2015 referendum changing Armenia's form of government to a parliamentary system instead of a quasi-presidential system.
Over the past four days, thousands of demonstrators protesting against the nomination of Serzh Sargsyan.
Many in the crowd of protesters said Pashinian's call for the demonstrations to remain nonviolent helped convince them to join in.
He is expected to be elected by parliament on Tuesday.
The protests are aimed at blocking the country's former president's return to power in the new role of the all-powerful prime minister.
Some protesters chanted "Armenia without Serzh" and "Serzh is a liar".
About 10,000 people started marching toward parliament early Monday afternoon and were blocked by police using tear gas and stun grenades.
Ironically, Pashinian himself was taken to a hospital with cuts and an eye injury after police moved in to stop the opposition lawmaker and others from entering parliament on April 16. The "civil disobedience" actions began early in the morning and quickly attracted thousands of demonstrators, many of them university students.
Serzh Sarkisian, a shrewd former military officer, has been in charge of the landlocked South Caucasus nation of 2.9 million since winning a presidential vote in 2008.
The country's new figurehead president, Armen Sarkissian, was sworn in last week but his powers will be weaker under a new parliamentary system of government. For the first time, Armenia's president was selected by the National Assembly, rather than by popular vote.
Armenian third president, Serzh Sargsyan was elected as a Prime Minister as the result of the elections in the parliament.