(CNN) -- U.N. High Commissioner for Human Rights Navi Pillay on Tuesday expressed concerns over Israeli forces' use of live ammunition against protesters along the cease-fire line between the occupied Golan Heights and Syria, as well as reports that Syrian authorities encouraged the civilians to protest in an area where landmines had been planted.
Syrian state media reported 25 protesters were killed and more than 350 wounded when Israeli soldiers opened fire on demonstrators Sunday. Lt. Col. Avital Leibovich, an Israeli military spokeswoman, said 10 people died when fire bombs thrown by protesters detonated landmines.
The incident occurred as protesters called for an end to the occupation of the Golan Heights, as they marked the anniversary of the 1967 War during which Israel occupied the area. A similar demonstration three weeks before resulted in bloodshed, with 12 dead.
The United States and Israel have blamed Syria for the incident Sunday, saying it was provoked to divert international attention from the bloody crackdown in that country against dissidents protesting Bashar al-Assad's regime. More than 1,000 people have died since the Syrian government began a crackdown on demonstrators seeking government reforms, according to the United Nations.
The U.N. High Commissioner, however, stressed that Israel "has a duty to ensure that its security personnel avoid the use of excessive force," and urged Israel "to comply with its obligations under international human rights and international humanitarian law to ensure the protection of civilians," the U.N. agency said in a statement issued Tuesday from its Geneva, Switzerland office.
"However difficult the circumstances, the use of live ammunition against allegedly unarmed protesters, resulting in large numbers of deaths and injuries, inevitably raises the question of unnecessary and excessive use of force," Pillay said in the statement.
Pillay also admonished Syria, saying authorities "have an obligation to ensure that civilians are prevented from entering areas where landmines are planted."
Haim Waxman, Israel's deputy ambassador to the United Nations, said in a letter Monday to the U.N. secretary-general and the president of the Security Council that the incident "could not have taken place without the knowledge of the Syrian authorities."
Waxman wrote it was Syria's responsibility to prevent "the breach of the agreed disengagement line in accordance with its international obligations and Security Council resolutions," and he called on the international community to "convey a clear message to Syria that such provocations carry serious potential for escalation and must cease completely."
Waxman said Israel Defense Forces "acted with maximum restraint in confronting the significant threat of violence facing it."
These individuals tried to break through fences in the area, threw Molotov cocktails and other large objects at the Israel Defense Forces, and used other violent means," Waxman said in the letter.
"The IDF acted with maximum restraint but with determination to prevent any breach of the disengagement line," Waxman's letter said. "To this end, it took numerous measures, including issuing clear warnings in Arabic over IDF loudspeakers about the serious dangers associated with attempting to breach the disengagement line."
Also, he said, Israeli forces stopped their operations several times to allow Red Cross personnel to "access the area and treat the wounded," but "many of the protesters continued to act violently."
Speaking at the Knesset, Israel's parliament, on Monday, Prime Minister Benjamin Netanyahu said Israeli troops used tear gas and live ammunition on demonstrators only "after using up all other means." The soldiers followed international law, he said.
"We stand by our rights to defend our borders, our cities and our citizens," he said. "We will do it with restraint and great responsibility.
"There is an attempt here to incite the international community and to draw attention away from the harsh events" in Hama, Netanyahu said.
Human rights groups have reported that 80 people were killed when security forces sprayed bullets into a crowd of protesters in Hama, Syria's fourth-largest city.
On Monday, the United States defended Israel's response.
"As we did previously, we condemn what appears to be an effort by the Syrian government to incite events and draw attention away from its own internal issues," State Department spokesman Mark Toner said. "And it's clear that such behavior will not distract international attention on Syria's, Syrian government's condemnable behavior on its own citizens."
As many as 500 people took part in the protests Sunday. They held midday prayers on the Syrian side of the border, then came down from a hill known locally as "Shouting Hill," where people shout to family and friends on the other side of the border.
They crouched down behind ramparts that Israel constructed in response to similar clashes on May 15, in which 12 people were killed.
Leibovich, the IDF lieutenant colonel, said Israeli troops were better prepared to deal with the demonstrations than they were three weeks before, having beefed up forces along the frontier. She said it was made clear "that we would not tolerate any infiltration into the Israeli side."
CNN's Mike Pearson, Kevin Flower, Mike Schwartz and Kareem Khadder contributed to this report.
