President Obama sought to convince Israeli Prime Minister Benjamin Netanyahu on Monday that he would not allow Iran to develop a nuclear weapon, but their meeting concluded with U.S. officials unsure whether the president had succeeded in persuading the Israelis to hold off on unilateral military action.

The leaders met for about two hours in the Oval Office at a crucial juncture in Obama’s effort to restrain Iran’s nuclear ambitions and win the trust of Israel, the closest U.S. ally in the Middle East. Israeli officials afterward called the talks “positive” and said both sides agreed on the need to continue economic and political pressure on Iran.

But hours after the meeting, Netanyahu renewed his warning that time for diplomacy was running out. In a fiery speech to a Jewish American advocacy group, he said recent economic sanctions had not slowed Iran’s march to nuclear-weapons capability.

“None of us can afford to wait much longer,” Netanyahu told a cheering audience at the American Israel Public Affairs Committee’s annual policy conference in Washington. “As prime minister of Israel, I will never allow my people to live in the shadow of annihilation.”

At the White House meeting, Obama made clear to Netanyahu that his policy is not to contain an Iranian nuclear arsenal but to prevent Iran’s leaders from developing one, administration officials said. In making his case for diplomacy over a military strike, Obama also assured Netanyahu that Israel has the right to act in its own national security interests.

“Our assessment is that they have not made a decision,” said a senior administration official, who spoke on the condition of anonymity to discuss the private meeting. “While I can’t say for sure that we bought time, I think they certainly feel more assured about our intentions. They can say and feel that the ball had moved forward in that respect.”

In public and private statements in recent days, Obama urged Israel to refrain from a military strike against Iran’s nuclear facilities, a move that many in the administration feared would set off a regional war in the volatile Middle East. Such a conflict in the oil-rich region would send gasoline prices even higher, exacerbating an election-year threat to Obama.

A few months would allow for the full array of economic sanctions against Iran to take effect this summer, including an embargo on its lifeblood oil industry and banking sector. That time would also help preserve the international coalition that is aligned against Iran’s nuclear program — a fragile diplomatic front that administration officials say would shatter if Israel struck prematurely.

“We do believe that there is a window that allows for a diplomatic resolution to this issue, but ultimately the Iranians’ regime has to make a decision to move in that direction, a decision they have not made thus far,” Obama said, with Netanyahu sitting at his side. “I reserve all options, and my policy here is not going to be one of containment. My policy is prevention of Iran obtaining nuclear weapons.”

Fear of Iran’s intent

Netanyahu, in his speech late Monday, said his government would prefer a peaceful resolution if Iran could be persuaded to abandon its nuclear ambitions. But if that doesn’t happen, he said, Israel was prepared to act unilaterally to stop Iran from acquiring the bomb — an act that he said would embolden Iran and its allied militant groups and raise the specter of nuclear terrorism and a nuclear arms race in the Middle East.

“Think how they’ll behave tomorrow with nuclear weapons,” Netanyahu told AIPAC. “Iran will be even more reckless and a lot more dangerous.”

While acknowledging that a military strike would be costly, he said: “I think we ought to start talking about the cost of not stopping Iran.”

Israel, which has its own undeclared arsenal of nuclear weapons, has concluded that Iran’s leadership has decided to pursue one as well. International inspectors have uncovered evidence to suggest a military intent for a program that Iran says is meant only for civilian power purposes.

Those concerns were underscored Monday at a meeting of the United Nations’ nuclear watchdog in the Austrian capital. Yukiya Amano, director general of the International Atomic Energy Agency, said the U.N. group has “serious concerns regarding possible military dimensions to Iran’s nuclear program.”

He voiced concern about Iran’s recent tripling of its production of a more-purified form of enriched uranium.

But the Obama administration is not convinced that Iran’s leaders have decided to develop a nuclear weapon, although U.S. diplomats have worked with European allies to implement oil and banking sanctions against Iran until it gives up its uranium-enrichment program.

Points of convergence

Before the Oval Office meeting, Netanyahu said: “Americans know that Israel and the United States share common values, that we defend common interests, that we face common enemies. Iran’s leaders know that, too. For them, you’re the Great Satan, we’re the Little Satan. For them, we are you, and you’re us.”

Obama and Netanyahu have been at odds in the past, particularly over how to revive the moribund Israeli-Palestinian peace process.

But the leaders share many of the same security goals. As Obama noted in his address Sunday to AIPAC, U.S. military aid to Israel has increased during each year of his administration.

Obama also has thrown the weight of U.S. diplomacy behind Israel. Last fall, he opposed the Palestinian bid for statehood at the United Nations. With the Palestinian peace negotiations a secondary issue, Obama and Netanyahu appeared more at ease than they did a year ago.

Israeli officials described the talks, which included a half-hour session just between the two leaders, as cordial. Obama and Netanyahu expressed resolve about preventing the emergence of a nuclear-armed Iran and promised an “open channel” going forward, a senior Israeli diplomat said.

Obama also publicly assured Netanyahu that the United States “will always have Israel’s back” when it comes to security, and the Israeli leader thanked him for his strong speech before AIPAC the previous day.

In those remarks, Obama declared that “all elements of American power” were still available to stop Iran’s enrichment program.

Heading into the meeting, Netanyahu and his national security advisers hoped to hear more explicitly from Obama about how he viewed the goal of the Iranian nuclear program and his timeline for moving against it.

The senior administration official said, “Our red line is a nuclear weapon, and we didn’t change our policy.”

“They didn’t press on the red line, but one thing they did press on was intent,” the official said. “They don’t trust this [Iranian] regime at all, and we don’t either. But we believe the pressure is mounting and that Iran may take some steps to relieve it.”

Staff writer David Nakamura contributed to this report.