The Israeli military says 14,000 Palestinian protesters thronged border areas on Friday.
More than 100 are reported wounded by Israeli gunfire as thousands of Gazans gather along the border fence.
President Mahmoud Abbas has given himself virtual veto power over any American initiative in the Gaza Strip.
The boys were among seven Palestinians fatally shot by soldiers during protests Friday against Israel's occupation.
The shootings occur as thousands of Palestinians gather along the frontier in response to calls by Hamas.
In the last five months, three emergency workers treating wounded protesters have been killed by Israeli army fire, while dozens more have been hurt by live fire or tear gas.
The move comes as President Trump and his Middle East point men, Jared Kushner and Jason Greenblatt, prepare for the rollout of a much-vaunted but as yet unclear peace plan for Israel and the Palestinians.
Israeli Ambassador Danny Damon responds to Antonio Guterres' report by saying that "the only protection the Palestinian people need is from their own leadership."
The filmmaker, journalist and refugee describes living conditions of Palestinians under the state of Israel and condemns the alliance between Donald Trump and Benjamin Netanyahu.