"We're not standing with a stopwatch in hand," he said in an Israeli TV interview, one of three he gave after returning from the United States and a White House meeting in which President Barack Obama urged him to give diplomacy and economic sanctions a chance to work before resorting to military action.
"It's not a matter of days or weeks, but also not of years," Netanyahu said.
If diplomacy and economic sanctions work, "then great," he said.
But "the result must be removal of the threat of nuclear weapons in Iran's hands," he said, asserting Israel faces "an existential threat" -- a threat with the potential to destroy, or drastically restrict, Israeli civilization.
U.S., Israeli and European officials, supported by U.N. weapons inspectors, maintain Iran plans to build nuclear weapons. Tehran insists its nuclear program is for peaceful civilian uses only.
Israel has repeatedly said it would not let Iran reach nuclear-weapons capacity and has declared it has an option to launch a military strike against Iran's nuclear facilities as a last resort.
White House spokesman Jay Carney said in Washington Thursday, "The Israelis, as I understand it, made clear [to the Obama administration] that they have not made a decision about taking that kind of action."
Carney denied an Israeli newspaper report Obama offered Netanyahu tacit support for an attack on Iran and advanced weapons, including the latest "bunker buster" bombs designed to penetrate hardened targets or targets buried deep underground, in exchange for a promise Israel would not strike this year.
"There was no such agreement proposed or reached," Carney told reporters.
When pressed on whether he was denying Washington was providing Israel with the U.S. Air Force's new precision-guided, 14-ton bunker buster known as the Massive Ordnance Penetrator GBU-57A/B, Carney said, "I am simply saying that it is my understanding that there was no such agreement discussed or reached in the meetings the president had."
"I hope there won't be a war at all, and that the pressure on Iran will succeed," Netanyahu said, affirming to a TV station he would prefer for Iran to halt its nuclear program and dismantle a uranium-enrichment facility located in an underground site near Qom, about 90 miles southwest of Tehran.
"That would make me happiest," he said. "I think every citizen of Israel would be happy."