Syria said 23 people were killed in Sunday's protest near the Golan Heights, when Israeli troops fired at Palestinian demonstrators who marched to the frontier fence.
Official news agency SANA quoted health minister Wael al-Halki as saying the death toll included a woman and a child, adding that another 350 people suffered gunshot wounds.
Three weeks ago Israeli soldiers shot dead 13 Palestinian protesters who tried to breach Israel's frontier with Lebanon and Syria during protests marking what Palestinians call the "catastrophe" of Israel's founding in 1948.
Sunday's protest was held to mark the 44th anniversary of the Arab defeat in the 1967 Middle East war, when Israel captured the Golan Heights, as well as the West Bank and the Gaza Strip, where Palestinians want to establish a state.
Palestinians in Syria marched down from a hilltop overlooking the Druze village of Majdal Shams on Sunday to the Israeli frontier, which before last month had been mostly peaceful for decades.
Israel has accused Syrian President Bashar al-Assad of allowing the Golan protests to try to divert the world's attention from his bloody suppression of the popular revolt against his authoritarian rule.
Israel is concerned that protests by unarmed demonstrators are a new tactic for Palestinians, adopted from popular revolts in the Arab world, to draw a violent response and gain more sympathy internationally for their cause.