Hamas calls those on the Gaza aid convoy as heroes of the Palestinian nation, urging Arab leaders to take practical steps to end the Gaza siege.
Gaza Freedom Flotilla came under fire early on Monday by Israeli navy forces in international waters more than 150km (90 miles) off the coast of Gaza.
At least 20 people were killed in the attack and more than 50 others were wounded.
"The Palestinian government honors the convoy’s effort to break the siege," Palestine’s democratically elected Prime Minister Ismail Haniyeh said in a statement.
"We consider all of the killed as Palestinian martyrs, martyrs of the siege on Gaza," he added.
The Palestinian leader called on supporters of the Palestinian cause to turn out in large numbers and protest what condemned as the Israeli "crime" and an act of piracy.
Haniyeh further urged the Palestinian Authority to end all negotiations with the Israeli regime in protest to "the violation of simplest and most clear of human rights."
He also called on the Arab League and the Organization of Islamic Conference (OIC) to take "practical measures" to permanently put an end to the years-long Israeli blockade of Gaza.