The United Nations has asked both the Sri Lankan Government and Tamil tiger rebels to stop fighting and resume peace talks.
"Sri Lankans continue to suffer deeply due to this conflict, and yesterday's loss of life is a source of deepest concern," Margareta Wahlstrwm, UN Assistant Secretary-General for Humanitarian Affairs and Acting Emergency Relief Coordinator, said.
"It is imperative that both sides in the conflict take all measures to fulfill their obligations under international law to protect civilians in this conflict. We have too often seen them fall short in this duty," she said.
The killings, the United Nations said, took place in north-western Sri Lanka during the aerial bombardment of the LTTE-controlled coastal village of Illupaikadavai in Mannar District by the Sri Lankan Air Force.
A number of children were reported to be among the killed and at least 35 other civilians were injured.
Some 3,000 civilians have been killed in the conflict since the resumption of armed hostilities last year, bringing the total number killed to 67,000, according statistics provided by the UN.
More than half a million Sri Lankans have been forced to flee their homes throughout the country, nearly 213,000 of them are newly displaced since the resumption of hostilities.