A ground attack on the Gaza Strip is a "clear possibility" as Israel’s frustration with the Hamas-controlled territory swells, a spokesperson for Israeli Prime Minister Benjamin Netanyahu said Sunday.

In an interview with CTV’s Question Period, Netanyahu spokesperson Mark Regev said Israel’s ultimate goal is to ensure that its citizens are no longer on the receiving end of Palestinian rocket fire. The state, however, still hasn’t decided how it’s going to achieve that end.

“Diplomatic discussions" are ongoing, he said, but without a lasting cease-fire agreement other options are being considered in parallel.

"It will stop one way or another," he said, adding, "A military option, a military incursion, a ground incursion is a clear possibility."

Netanyahu echoed that statement later Sunday, at the opening of his weekly cabinet meeting.

“The Israeli military is prepared to significantly expand the operation,” Netanyahu said before the meeting got underway.

Holding up Canada and the United States as examples, Regev said that no country would tolerate the ongoing rocket attacks that Israel has been deflecting with its “Iron Dome” defence system.

While Canada has supported Israel’s decision to defend itself, it’s unclear whether that support would extend to a ground invasion.

Also speaking to Question Period, Defence Minister Peter MacKay said international observers have been urging both Israel and Hamas to exhaust all diplomatic avenues.

“We are engaged in what I consider to be constructive dialogue, calling upon people who have influence on Hamas, influence on this situation and its potential outcome to continue to press for restraint,” MacKay said in an interview from the Halifax International Security Forum.

Israel’s campaign received measured support from U.S. President Barack Obama on Sunday, who asserted that the country is within its rights to defend itself from Hamas-launched attacks.

"There’s no country on Earth that would tolerate missiles raining down on its citizens from outside its borders," said Obama, speaking at a news conference in Bangkok, Thailand.

Obama’s declaration comes during the fifth day of Israel’s campaign against rockets fired from the Hamas-controlled Gaza Strip, where Palestinian militants have stoked historic tensions with missiles aimed at Tel Aviv and Jerusalem. In its most recent threat against the territory, Israel vowed to expand its attacks against Gaza Sunday, pledging to go after Hamas military commanders.

The latest violence between the two regions saw Israeli airstrikes hit two Gaza media centres Sunday morning, while militants again took aim at Tel Aviv with long-range rockets. Israel airstrikes also hit more than a dozen homes belonging to Hamas militants. Security officials said at least 11 civilians, including four children, were killed -- the dispute’s highest one-day civilian toll yet.

In the meantime, Obama voiced his support for the Israeli campaign, saying that the growing hostilities were precipitated by an "ever-escalating" number of missiles landing in the Middle Eastern country.

"We are fully supportive of Israel’s right to defend itself from missiles landing on people’s homes and workplaces and potentially killing civilians," he said, adding, "what is also true is that we are actively working with all parties in the region."

Similarly, Canadian Prime Minister Stephen Harper also maintains that Israel has the right to defend itself. Speaking to reporters on Friday, Harper condemned Hamas’ attacks against Israel.

"We recognize and support Israel's right to defend itself against such terrorist attacks,” said Harper. “But obviously, we urge all sides to take all precautions possible to spare any innocent lives.”

According to Regev, Netanyahu has been in contact with Harper, who has been a vocal supporter of Israel in the past. Regev did not elaborate on what was discussed, only saying that he believes the two are “good friends” who had a “good conversation.”

At least 81 Palestinians have been killed since a campaign against Gaza began Wednesday, while in Israel, three civilians have been killed and more than 50 others have been wounded by rocket fire.

In a bid to stop the conflict, Egypt is attempting to broker a ceasefire between Israel and Hamas. According to the office of Gaza Prime Minister Ismail Haniyeh, the Hamas leader spoke with Egyptian President Mohammed Morsi in a 20-minute long phone call about a potential truce.

Any agreement, however, will likely be hard earned as Israel has stated in no uncertain terms that it will not enter a ceasefire unless it is reassured that Palestinian rocket fire will not continue.

“If a ceasefire is just a Band-Aid, just a quick fix, and a week from now we’re going to have rockets again, we’re not interested,” Regev told Question Period.

Israel and Gaza’s Hamas rulers continue to differ on the terms that would accompany a potential truce. Hamas wants Israel to lift its border blockade on Gaza, and seeks reassurance that Israel will stop targeted killings of leaders and military commanders. Israel has rejected the requests.

The conflict appeared to have entered an aggressive new phase on Sunday as Israel came through on its pledge to strike the homes of suspected Hamas military commanders. The Sunday airstrikes levelled homes in a densely populated part of Gaza, leaving residents stranded beneath rubble.

Israel has accused Hamas of putting its own residents in the line of fire by using residential areas for cover. It’s also accused the territory of deliberately targeting Israeli civilians.

“They’re feeling pain at the moment and it’s clear that they’d like an immediate ceasefire, but the question is: Is that good?” said Regev. 

“If in just a week from now they’re going to be at their games again, shooting rockets into Israel, it achieves nothing. We want to come out of this with a sustained period of quiet.”

With files from The Associated Press