The Islamic movement Hamas that rules Gaza and which has fought three wars with Israel since 2008 has said five of the dead were members of its armed wing.
Global human rights groups criticized Israel's use of live ammunition on the protesters, while U.N. Secretary-General Antonio Guterres called for an inquiry into the deaths.
In Friday's march, thousands of Palestinians Israel estimated a turnout of 35,000 headed toward the border area along several points from the north to the south of Gaza.
Along with firebombs and rocks, organizers of the protests have stockpiled tires, to be set on fire and hurled at the security fence. Israeli troops were lined up on the other side of the fence, including snipers perched on high earth embankments overlooking Gaza.
More than 750 Palestinians were wounded by Israeli fire in Friday's protest, according to Gaza health officials, making it the bloodiest day in Gaza since the 2014 Israel-Hamas war.
It said there were attempts to damage the fence and infiltrate Israel, while alleging there was also an attempted gun attack against soldiers along the border.
"The high number of deaths and injuries was the foreseeable effect of granting soldiers leeway to use lethal force outside of life-threatening situations in violation of worldwide norms, coupled with the longstanding culture of impunity within the Israeli army for serious abuses", the group said.
Gaza health officials said an additional 800 protesters were injured by live fire.
Israel's defence minister, Avigdor Lieberman, ruled out participation in any commission of inquiry, telling Army Radio on Sunday that the Israeli military "did what had to be done".
The United Nations has demanded an "independent and transparent investigation" into Israel's actions during the riots.
Israeli Defence Minister Avigdor Lieberman has rejected worldwide calls for an investigation. "Every person who approaches the fence is endangering his life".
Israel's military spokesman, Brig.
Adli Abu Taha, who filmed the scene on his mobile phone, told The Associated Press that Abu Shanab had thrown stones close to the fence before joining the group for Friday prayers.
The Left-wing group B'Tselem said that Liberman's decision to continue to order his soldiers to shoot at demonstrators was frightening and illegal. He argued that there would have been far more bloodshed in the event of a mass border breach.
They felt they had little to lose because of dire poverty in Gaza and that they would return to protest once they had recovered.
Arkab had been protesting east of Khan Yunis, in the southern Gaza Strip. About 150 tires of all sizes were piled up at a traffic circle Tuesday, waiting to be transported to the nearby tent camp.
He warned Palestinians to stay away from the border and said Hamas was responsible for any violence that took place. Two other blockade-busting strategies - war with Israel and reconciliation with Abbas - have failed.
Ahead of the mass demonstrations, Israel deployed thousands of troops along the border.
Friday's rallies were the start of a six-week protest that culminates on May 15, the day the Palestinians call as "Nakba", or "Catastrophe" when Israel was created. Most of Gaza's 2 million people are descendants of Palestinian refugees. Life in Gaza has become increasingly harsh after more than a decade of closures, with residents enduring daily power outages lasting hours.