A U.N. representative says Israel used "disproportionate, deadly force" when its soldiers fired on demonstrators marching toward the country's borders.
The statement Monday by U.N. special coordinator for Lebanon Michael Williams was unusually forceful. He said he was "shocked" by the number of deaths and urged both sides to show restraint.
Thousands of Arab protesters marched toward Israel's borders with Syria, Lebanon and Gaza on Sunday in an unprecedented wave of demonstrations.
The ensuing clashes left at least 15 people dead, including 10 Palestinians in Lebanon.
Sunday's clash in Lebanon was the deadliest incident along the volatile border in five years.