President Barack Obama said Sunday the United States won't hesitate to use force to halt Iran from acquiring a nuclear weapon, something he says could trigger an arms race in one of the world’s most volatile regions.

"I will not hesitate to use force when it's necessary to defend the United States and its interests," says Obama, speaking to thousands of delegates to the policy conference of the American-Israel Public Affairs Committee (AIPAC) in Washington.

Obama also stressed that "too much loose talk of war" in recent weeks has only helped Tehran and boosted oil prices.

The Israeli government has recently been suggesting that Israel is considering launching a military attack on Iran's nuclear facilities. Iran, however, maintains its nuclear program is for peaceful purposes.

But while the U.S. is ready to unleash against Iran if need be, Obama said he also urged Israel to allow further sanctions against Iran to take hold, and put pressure on Tehran, rather than have the threat of nuclear war result in a unilateral Israeli strike against Iran's nuclear facilities.

"For the sake of Israel's security, America's security, and the peace and security of the world, now is not the time for bluster," Obama said. "Now is the time to let our increased pressure sink in, and to sustain the broad international coalition that we have built."

Canada, the U.S. and the U.K. are limiting Iran's access to much of the world's financial system in an attempt to isolate the country's regime, with the toughest sanctions, targeting Iran's oil business and central bank, are to take effect this summer.

Obama added that he is sympathetic to Israel's concerns.

"No Israeli government can tolerate a nuclear weapon in the hands of a regime that denies the Holocaust ... and sponsors terrorist groups committed to Israel's destruction," added Obama.

"So I understand the profound historical obligation that weighs on the shoulders of [Israeli Prime Minister Benjamin] Netanhayu and all of Israel's leaders."

While any Iranian nuclear efforts run counter to Israeli security interests, as well as those of the U.S., and "Israel as a Jewish and democratic state must be protected ... the entire world has an interest in preventing Iran from acquiring a nuclear weapon," Obama stressed.

In Israel, Foreign Minister Avigdor Lieberman said American pressure would not affect Israeli thinking on how to cope with the threat.

"We are an independent sovereign state, and at the end of the day, the state of Israel will make the most correct decisions as we understand them."

Obama's speech came the day before his meeting at the White House with Netanyahu, and two days after the Israeli prime minister met with Canadian Prime Minister Stephen Harper in Ottawa.

Netanyahu 'heartened' by Obama speech: Fogel

During a joint news conference with Netanyahu, Harper said Canada wants a "peaceful resolution" to prevent further development of Iran's nuclear program. Netanyahu, however, said "all options" to stop Iran from acquiring nuclear weapons should be on the table.

Netanyahu said there is a "sea of troubles" in his region, but most disturbing among them is the "relentless Iranian pursuit of arming themselves with nuclear weapons."

Harper was asked whether Canada would support a pre-emptive strike on Iran, and he said the country's intentions and capabilities remain "a serious concern" to Canada.

Netanyahu left Ottawa for Washington on Sunday afternoon, after meeting with CEO Shimon Fogel of the Centre for Israel and Jewish Affairs. Fogel told CBC News he discussed the situation in Iran, the peace process with the Palestinianas and other issues with Netanyahu.

Fogel said he believes Netanyahu "was pretty heartened by the messages that he heard Barack Obama convey" Sunday morning.

"What came out of the Obama speech was a re-enforcement of those things that actually point to an emerging consensus between Israel, Canada, the U.S., the European community about the need to confront Iran — that there is nothing off the table, and that a nuclear Iran is not a situation that can be contemplated by the West."

However, Fogel said, "everybody, Israel included, really does want to see every effort expended towards achieving a dilomatic or political solution."

Netanyahu plans to address the AIPAC conference late Monday. As well, three of the four Republican presidential candidates — Mitt Romney, Rick Santorum and Newt Gingrich — were scheduled to speak to the conference via satellite on Tuesday, a critical day in the campaign when 10 states vote.

The candidates have accused Obama of failing to slow down Iran's nuclear pursuit. But Obama says world is more united than ever against Iran, and he blames Republicans for trying to drive a wedge between him and Jewish voters.

"You've had no evidence that the president is prepared to take steps to stop Iran from getting nuclear weapons. They talk and the Iranians build. They talk and the Iranians build," said Gingrich said before Obama's speech. "We're being played for fools."