"And this will give more time for sanctions and diplomacy to convince Iran to dismantle its nuclear weapons program altogether," he added.
Netanyahu's remarks were the closest he or any top Israeli official has come to publicly laying out precisely which Iranian actions could trigger an Israeli military strike on Tehran's nuclear infrastructure.
But by referring to a spring or summer 2013 time frame for Iran to complete the next stage of uranium enrichment, the Israeli leader also seemed to dispel, at least for now, fears that Israel might strike Iran before the U.S. presidential election, 40 days away.
Netanyahu's remarks also seemed to deliver a two-part message to the Obama White House - along with Iran's leaders, his most important audience - signalling that the hawkish prime minister wanted an end to the all-too-public war of words with Washington over Iran's suspected nuclear ambitions. But they also showed he was not backing down an inch on his insistence that much harsher warnings must be delivered to Tehran.
In his speech, Netanyahu never explicitly said that if Iran crossed his red line, Israel would launch attacks against the Iranian nuclear facilities, but he did seem to imply such a threat.
"At this late hour, there is only one way to peacefully prevent Iran from getting atomic bombs. That's by placing a clear red line on Iran's nuclear program," Netanyahu said.
Iran, Netanyahu said, was well into what he defined as the second stage of enrichment - 20 percent purification - and predicted it would complete it by "next spring, at most by next summer, at current enrichment rates."