Speaking on CNN's "State of the Union" program, Netanyahu said Iran is "moving very rapidly" toward completing the enrichment of enough uranium to produce a nuclear bomb.
"In six months or so they'll be 90 percent of the way there," the Israeli leader said. "I think it's important to place a red line before Iran. And I think that actually reduces the chance of military conflict because if they know there's a point, a stage in the enrichment or other nuclear activities that they cannot cross because they'll face consequences, I think they'll actually not cross it."
Netanyahu likened the situation the 1962 Cuban missile crisis in which U.S. President John F. Kennedy faced down Soviet Premier Nikita Khrushchev over the placement of Soviet missiles in Cuba.
"He [Kennedy] was criticized for it, but it actually pushed back the world from conflict and maybe purchase decades of peace," Netanyahu said
He said the first Iraq War may have been averted if a line had been drawn with Iraqi leader Saddam Hussein before he invaded Kuwait. He added Iran has backed down in the past when clear lines have been drawn on various issues.
Asked if he thinks President Obama's repeated statement that it would be unacceptable for Iran to have a nuclear weapon was a clear enough warning to Tehran, Netanyahu said he thinks that implicitly means Obama would act to stop it from happening, but that needs to be communicated to Tehran.
"I wouldn't bet ... the security of the world and my own country's future from a country that threatens our annihilation, murders civilians en masse in Syria and brutalizes its own people," he said.
He also said he doesn't believe Iran only wants nuclear capabilities of civilian purposes as it claims.
"... It's not legitimate," he said. "This is a country that talks about -- denies the holocaust, promises to wipe out Israel, is engaged in terror throughout the world. It's like Timothy McVeigh walking into a shop in Oklahoma City and saying I like to tend my garden. I would like to buy some fertilizer.
How much do you want? Oh, I don't know, 20,000 pounds.
"Come on. We know that they're working towards a weapon. We have absolutely certainty about that."
Netanyahu said his sense of urgency is not dictated by "the American political calendar, it's the Iranian nuclear calendar."
Members of Congress to keep receiving porn magazine
Rosie O'Donnell unveils nearly 50-pound weight loss