The number of Palestinians killed by Israeli troops reached 18 on Monday when a 29-year-old man died of injuries from army fire.
The young Gazan had taken part in the mass protests on the border with Israel, where more than 1,400 people were wounded.
Israeli troops used live bullets, rubber-coated steel pellets and tear gas, prompting rights groups to condemn the shooting of Palestinians who don't pose a threat to soldiers' lives.
The march was mobilised by Hamas and was the first in six weeks of protests set to culminate on May 15, the day after the anniversary of the official establishment of Israel and 70 years since Nakba - the displacement of 700,000 Palestinians.
Israel rejected allegations of excessive force, saying it defended its border against what it claims is a Hamas attack under the guise of mass protests. It says troops were instructed to target "the main instigators."
Israel defended its soldiers' actions on Friday, when they opened fire on Palestinians who strayed from a main protest camp and approached the heavily fortified fence cutting off the blockaded Gaza Strip.
The military said soldiers opened fire only when necessary against those throwing stones and firebombs or rolling tyres at soldiers.
The armed wing of Hamas said five of those killed were its members who were participating "in popular events side-by-side with their people".
The Israeli army alleges 10 of the dead had "documented terror backgrounds" in Hamas and other groups and were killed "whilst carrying out acts of terror".
Israel's defense authorities confirmed that Israel is holding the bodies of two alleged Hamas members. There were no casualties among Israelis.
On Monday both sides braced themselves for further tensions after Palestinians called for more demonstrations.
"The Palestinian people are determined to continue the great 'March of Return,' to free the land and move towards occupied Jerusalem, and they are not concerned by all the sacrifices," senior Hamas member Khalil Al Hayya told a memorial ceremony, while also vowing that his group would not disarm.