Pashinyan conveyed his sympathies to Leader of the Islamic Revolution Ayatollah Seyed Ali Khamenei in a message.
"I am shocked by the tragic loss of Iran's President Ebrahim Raisi and his accompanying staff in the helicopter crash," Pashinyan said.
"On behalf of the government and people of Armenia, I offer my heartfelt condolences for the passing of my dear friend and colleague, President Ebrahim Raisi, Foreign Minister Hossein Amirabdollahian, and their companions.
"I express my solidarity with the government and people of the Islamic Republic of Iran and wish them patience and strength in this difficult time.
"The Republic of Armenia and its people stand by our good neighbor and friend, the Islamic Republic of Iran, in this challenging period."
Early Monday, it was confirmed that President Raisi had been martyred in the crash in the Varzaqan region of East Azerbaijan province, northwest of Iran. Raisi was accompanied by Ayatollah Mohammad Ali Ale-Hashem, the Friday Imam of Tabriz, Foreign Minister Hossein Amirabdollahian, and East Azerbaijan Governor Malek Rahmati, who were also martyred in the crash. Other victims included Maj. Gen. Seyed Mehdi Mousavi, head of the president’s security team, a member of the Ansar al-Mahdi Corps, the helicopter pilot and co-pilot, and a helicopter technician.