Israel's ambassador to Washington said on US television that his country rejects any international investigation. "We are rejecting the idea of an international commission," Michael Oren told "Fox News Sunday."
"Israel is a democracy. Israel has the ability and the right to investigate itself, not to be investigated by any international board," he added.
Foreign Minister Avigdor Lieberman is to travel to New York on Monday to brief Israeli ambassadors posted in North America on the government's position on the aid flotilla, his ministry said.
Also on the international front, France's President Nicolas Sarkozy asked Israeli Prime Minister Benjamin Netanyahu to accept "a credible and impartial inquiry" into the deadly raid, the French leader's office said.
Late Sunday Netanyahu's office issued a statement confirming he had talked with Sarkozy as well US Vice President Joe Biden.
"During these talks the prime minister stressed that Israel had acted in this affair like any country threatened with thousands of rockets and missiles," the statement said, referring to attacks against Israeli territory by militants in Gaza.
Meanwhile, the Palestinian Islamist movement Hamas, which rules Gaza, hailed the latest bid to break Israel's blockade.
"We condemn the continuing policy of terrorism implemented by Israel against the Palestinian people and activists for peace and freedom," it added in a statement released from its base in exile in Damascus.
In a first batch, seven of 19 activists from the Rachel Corrie aid ship which tried to run the Gaza siege were expelled from Israel to Jordan on Sunday. The remaining 12 were due to be flown home overnight, officials said.
The five Irish nationals, including Nobel Peace laureate Mairead Maguire, were expected to leave on a flight to Dublin leaving early on Monday at around 5:00 am (0200 GMT).
Until then, they were waiting in a special section of the airport without access to their mobile phones, although they had access to consular assistance, immigration officials said.
Israeli forces took control of the boat on Saturday as it tried to reach Gaza, in a peaceful operation that contrasted with the May 31 raid when commandos stormed a Turkish boat packed with more than 600 passengers.
Israel says its commandos only resorted to force after being attacked as they reached the deck, but activists claim the soldiers started firing first.
Amid increased regional tensions, an aide to Iran's supreme guide, Ayatollah Ali Khamenei, said that the Islamic republic's elite Revolutionary Guards would be prepared to escort cargo ships on blockade-busting missions.
Although Israeli leaders have dismissed suggestions that the siege of Gaza should be eased, last week's bloodshed should be used as an opportunity to press Israel to change its policy on Gaza, a senior UN official said.
"We very much want to see what's happened -- or use what's happened, tragic as it is -- as an opportunity to try to ... persuade Israel to change policy," said John Holmes, Under Secretary-General for Humanitarian Affairs.
Speaking to AFP in Sydney, Holmes said the blockade was "unacceptable, counterproductive, (and) very damaging for the people of Gaza."
Britain, too, joined a growing chorus of calls for Israel to end the blockade, which was imposed in 2006 after Gaza-based Hamas militants kidnapped Israeli soldier Gilad Shalit, who is still being held.
"The humanitarian situation in Gaza is both unacceptable and unsustainable," International Development Secretary Andrew Mitchell said in London.
Turkey's Prime Minister Recep Tayyip Erdogan vowed to hold Israel to account over its "state terror" in the Middle East as thousands of Turks protested against the deadly raid.
And Pope Benedict XVI on Sunday called for an "urgent effort" to end bloodshed in the Middle East on the final day of a visit to Cyprus.
"I reiterate my personal appeal for an urgent and concerted international effort to resolve the ongoing tensions in the Middle East, especially before such conflicts lead to greater bloodshed," the pontiff said.