The blasts, which occurred in southern Lebanon, in the southern suburbs of Beirut known as Dahiyeh and the eastern Bekaa valley, killed at least eight people and wounded 2,750 others, 200 of them critically.
Reports showed ambulances rushing through the southern suburbs of the capital Beirut, with groups of people huddled at the entrance of buildings to check on people they knew who may have been wounded.
“It is with deep concern and alarm that we have received the news of the attacks in Lebanon,” said Pillay.
“We urgently call for peace amid an attack that only escalates warfare, and needlessly harms and kills innocent civilians. We are praying for all those people who were leading their daily lives and were injured, and those who are still searching frantically for their loved ones,” he said.