President Obama and Israeli Prime Minister Benjamin Netanyahu huddled in the Oval Office Monday, as the White House sought to assure the major U.S. ally that Obama's newly-launched talks with Iran would not bring harm to Israel.

Obama hosted Netanyahu at the White House Monday, just days after calling Iranian President Hassan Rouhani, the first such conversation between the two countries since 1979.

The 15-minute phone call between Obama and Rouhani was framed by the White House as a historic exchange that could open a new era of diplomacy between the United States and Iran over the Middle East nation’s much-debated nuclear aspirations.

But Netanyahu is highly skeptical of U.S.-Iranian talks, saying that such conversations are merely a stalling technique by Iran to fend off crippling international sanctions and expand its nuclear capabilities.

Obama looked to quell such concerns on Monday, focusing on international affairs even as Washington careens closer to a government shutdown.

“We agreed it is paramount that Iran doesn’t get nuclear weapons,” Obama told reporters, flanked by Netanyahu in the Oval Office.

“We have to test diplomacy,” Obama said of Iran, adding that just “words are not sufficient.”

Obama, who famously pledged in 2007 that he would pursue discussions with Iran, is being careful to convince U.S. allies — and critics at home — that he is not entering such talks with unrealistic expectations.

But friction over Iran could threaten Obama’s delicate relationship with Netanyahu. The president is also pressing the Israeli leader over peace negotiations with the Palestinians and new housing construction in the West Bank.

For his part, Netanyahu declared that the “most important challenge is preventing Iran from getting a nuclear weapon.”

And he urged Obama to keep economic sanctions in place against the Iranian regime.

In the face of widespread international skepticism, Iranian officials say they are committed to pursuing a peaceful energy program.

"Negotiations are on the table to discuss various aspects of Iran's enrichment program," Iranian Foreign Minister Javad Zarif said Sunday on ABC's "This Week."

Even ahead of the White House meeting, Netanyahu was telegraphing his disapproval of Obama’s decision to engage the leader of Iran, whom Netanyahu views as hell-bent on Israel’s destruction.

"I will tell the truth in the face of the sweet talk and the onslaught of smiles," Netanyahu said before flying to the United States. "Telling the truth today is vital for the security and peace of the world and, of course, it is vital for the security of the state of Israel."

The two leaders also discussed efforts to destroy Syrian President Bashar Assad’s stockpile of chemical weapons, a goal recently bolstered by a U.N. resolution calling for Assad’s arsenal to be turned over to the international community.