The ruling Republican Party and the government-friendly Armenian Revolutionary Federation formally nominated Sarkisian as candidate for the post of prime minister on Monday despite the protests.
Opposition supporters walk along a street during a rally in central Yerevan on April 16, 2018.
The protesters, many with Armenian flags in their hands, filled the Marshal Baghramyan Avenue leading to the building of the National Assembly, and at the same time blocked the traffic in the city centre.
The Armenian Health Ministry reported later that 46 people required medical assistance after the clash.
The Police have issued a statement, urging Nikol Pashinyan, leader of the anti-government protests, to comply with RA Law on the Freedom of Assembly, to stop blocking the streets and ensure the normal course of assembly.More news: America, Britain and France strike Syria
Throughout the day, Pashinyan kept stressing that "the police are our brothers" and repeatedly apologized to policemen for the inconvenience caused by the demonstrations and called on protesters not to attack police, verbally or otherwise.
Pashinian reached out to these and other opposition forces when he addressed the demonstrators in Liberty Square.
People oppose the appointment of former President Serzh Sargsyan, Prime Minister. And he again accused Sarkisian of breaking his 2014 pledge not to extend his rule if Armenia becomes a parliamentary republic.
His calls were answered by several thousand people who flocked to the parliament building.
Rallies began on Friday when more than 4,000 people took part.More news: Volkswagen names new boss to steer sweeping overhaul
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.
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.
Sargsyan rules Armenia in the role of a president since 2008.
He had promised in 2014 that he would "not aspire" to be prime minister if Armenia switched from a presidential to a parliamentary system as a result of the referendum, and Pashinian and other opposition leaders now accuse him of breaking that pledge.More news: Gmail is testing sending confidential emails that automatically expire