Tens of thousands take part in the procession every year, including many from Armenia's widespread diaspora who travel to Yerevan for the event.
"The republic of Armenia should double its efforts for the restoration of historical justice.
"When it comes to condemning the genocide, denial has no future, especially today when many countries around the world have added their voices to the voice of truth," Sarkisian said.
Armenians say they suffered discrimination, religious persecution, heavy taxation and armed attacks under Ottoman Turks since 16th century
Thousands killed from 1894 to 1896 during a crackdown on Armenian nationalists
Armenians claim 1.5m murdered or starved to death when Ottoman Turks deported them to Syria and Mesopotamia deserts from 1915-1917 during WWI
Turkey says inflated toll due to ethnic clashes, disease and famine
All ties between Turkey and Armenia severed more than 90 years ago
Tigran Sarkisian, the prime minister, said that the massacres showed the need for Armenian unity, a clear reference to post-election clashes last month between opposition supporters and riot police that left 10 dead.
The opposition claims Serzh Sarkisian's February win was rigged.
"We cannot be in safety and security if we are divided and separated. We cannot prevent major disasters from recurring if we fail to have a strong state," the prime minister said.
Armenians believe up to 1.5m people died in orchestrated killings during the final years of the Ottoman Empire.
Turkey says 300,000 Armenians and at least an equal number of Turks were killed in civil strife when the Christian Armenians, backed by Russia, rose up against the Ottomans.
The dispute has been a major obstacle in relations between Turkey and Armenia, which have no diplomatic ties and whose border has remained closed for more than a decade.
Ali Babacan, the Turkish foreign minister, said this week that Turkey was "open to dialogue" with Armenia's new government "with the aim of normalising Turkish-Armenian ties."
The controversy has also complicated relations between EU-aspirant Turkey and many Western countries, especially those with large ethnic-Armenian communities such as the United States and France.
Many taking part in Thursday's ceremony called on Western countries to pressure Turkey into recognising the massacres as genocide.
"I lost my entire family at the hands of the Turks," Srbuhi Pirumian, an 80-year-old Armenian said. "I will never tire of telling our history to my children and to my grandsons....The Turks have no place in Europe.
More than 20 countries, including Belgium, Canada, Poland and Switzerland, have officially recognised the killings as genocide.
In 2006, French lawmakers voted to make it a criminal offence to deny that Armenians were victims of genocide.
But many countries, including Britain and the United States, refuse to use the term to describe the events, mindful of relations with Turkey.