The United States said Sunday it is "deeply troubled" over clashes on the Syrian border with Israel that reportedly resulted in 20 deaths, and called for calm on both sides.
Meanwhile, the protestors said they were planning to stage a sit-down opposite the border throughout the night.
Israeli troops opened fire as protesters from Syria on Sunday stormed a ceasefire line in the Golan Heights.
"We are deeply troubled by events that took place earlier today in the Golan Heights resulting in injuries and the loss of life," the State Department said in a statement.
"We call for all sides to exercise restraint. Provocative actions like this should be avoided."
The US statement emphasized that "Israel, like any sovereign nation, has a right to defend itself."
Hundreds of protesters rushed towards the ceasefire line on Sunday, cutting through barbed wire as they tried to enter the Golan Heights in a repeat of demonstrations last month that saw thousands mass along Israel's north.
"Despite numerous warnings, both verbal and later warning shots in the air, dozens of Syrians continue to approach the border and IDF (Israel Defense Forces) forces were left with no choice but to open fire towards the feet of protesters in efforts to deter further actions," an Israeli army spokesman told AFP.
Roee Nahmias contributed to this report