Israeli Prime Minister Benjamin Netanyahu cut short his Canadian visit, after his military raided a Gaza-bound aid flotilla and killed at least nine people.

After shaking hands with Prime Minister Stephen Harper in Ottawa, Netanyahu acknowledged he would be returning to Jerusalem earlier than expected.

"I explained to the prime minister that I would have to cut my visit short and go back to Israel," he said Monday morning.

Netanyahu said he wished to reschedule his visit to Canada "at the earliest date possible."

Prime Minister Stephen Harper said Canada "deeply regrets" the raid on the flotilla, but said he understood Netanyahu's need to return home in a hurry.

"Obviously today, we're preoccupied with the events that occurred overnight and I understand you're obviously going to have to cut short your trip and return to Israel," Harper said.

He said that Canada would "be looking in the days that follow to get all the information we can get to find out exactly what has transpired here."

Harper discussed the incident with U.S. President Barack Obama Monday afternoon as the two leaders prepared for next month's G8 and G20 meeting.

Earlier Monday, Dimitri Soudas, the director of communications for Harper, said Ottawa was concerned about the deadly nature of the incident.

"Canada deeply regrets the loss of life and the injuries suffered," Soudas said in a statement released to media.

Netanyahu was previously due to attend a gala dinner in Ottawa this evening. He arrived in Canada on the weekend.

As a result of his quick return trip home, the Israeli prime minister will also skip a meeting with Obama that was scheduled to take place Tuesday.

Netanyahu said he believed that both Harper and Obama "understand that Israel has a great security problem."

Controversial raid

The controversial raid that prompted Netanyahu's return home occurred early Monday morning when Israeli soldiers stormed a Turkish-owned ship and became engaged in a confrontation.

Netanyahu said the soldiers were attacked and "had to defend themselves, defend their lives, or they would have been killed."

He said that Israel's policy is to allow humanitarian shipments into Gaza. But his country is always on watch for dangerous materials that could harm Israeli citizens.

"What we want to prevent coming into Gaza are rockets, missiles, explosives and war materials that could be used to attack our civilians," he said in Ottawa.

"This is an ongoing policy and it is the one that guided our actions yesterday."

He said his government regrets the loss of life that resulted from the raid.

Netanyahu said his country "has no quarrel with the people of Gaza."

"We do have a conflict with the terrorist regime of Hamas, supported by Iran."

Shortly after news of the raid broke, some Toronto residents began making their way to the Israeli consulate on Bloor St. for a peaceful protest.

By the dinner hour, an estimated 300 people were standing on one of the city's busiest streets, waving placards and denouncing the raid.

The group was scheduled to make its way down University Ave. and then across College St. to continue the protest at Yonge-Dundas square.

In a statement, Canadians for Justice and Peace in the Middle East said it believed Israel used "disproportionate force against civilians" and behaved in a "completely reprehensible" manner.

"The Canadian government's unwillingness to question Israel's conduct even in these most extreme circumstances is also disappointing and upsetting," the group said.

But B'nai Brith Canada alleged the flotilla was organized by Islamists "whose obvious goal was to provoke Israel into a response."

With files from The Canadian Press and The Associated Press, and CTV Toronto's Michelle Dube