Six Palestinians were shot dead protesting at the border fence.
The demonstration was called in solidarity with Palestinians in the occupied West Bank and Jerusalem and followed a spate of attacks by Palestinians against Israelis and reprisals by Jews against Arabs.
The Israeli army said around 200 Palestinians reached to within less than 100 metres of the border fence in northeast Gaza, throwing rocks and rolling burning tyres toward Israeli troops stationed on the other side.
The soldiers "fired at the main instigators in order to halt their advance and disperse the riot," a military spokeswoman said, adding that she knew of five Palestinians who were shot.
Hospital officials put the death toll at four, with 13 others wounded. Witnesses said they had been fired at by Israeli snipers in guardposts along the border fence, about 400 metres away from where the Palestinians were protesting.
There is an Israel-imposed security zone that runs about 300 metres from the border into Gaza. Hamas and other Palestinian militant groups have lookout towers and guardposts in place just back from the buffer zone.
The leader of Hamas in Gaza, Ismail Haniyeh, called on Palestinians to step up their fight against Israel, describing the recent surge in violence in Jerusalem and the occupied West Bank as the beginning of a new uprising, or intifada.
"This is Friday, this is the day of rage... It is a day that will represent the start of a new intifada in all of the land of Palestine," Haniyeh told followers after Friday prayers.
"We give souls and blood for Jerusalem, Jerusalem and Aqsa is part of the religion," he said, describing Palestinians who have carried out stabbings against Israelis as "heroes".
"Gaza stands beside the battle in Jerusalem... Gaza is fully ready," he added, saying all Palestinians should defend the Aqsa mosque compound in Jerusalem, the focus of tension with Israel.
