On the eve of a landmark speech to the US Congress, Netanyahu declared that a US-Iran deal on curtailing Tehran's nuclear ambitions "could threaten the survival of Israel."
He spoke even as US Secretary of State John Kerry and his Iranian counterpart Mohammad Javad Zarif met in Switzerland for a talks which are expected to end Wednesday. But Obama and his leading foreign policy officials did not leave the field to the Israeli leader, insisting their plan was the best way to contain Iran's alleged threat.
Obama and Netanyahu both insisted the traditional alliance between their countries remains strong, but the US leader pointedly criticized the Israeli's previous declarations.
Referring to criticism of a previous interim US-Iran deal that paved the way for this week's ongoing talks in Switzerland, Obama said: "Netanyahu made all sorts of claims. "This was going to be a terrible deal," he told Reuters.
"This was going to result in Iran getting $50 billion worth of relief. Iran would not abide by the agreement. None of that has come true."
Netanyahu's lobbying trip to Washington came as Kerry was in Geneva and culminates on Tuesday with the address to Congress, seen as a last-ditch bid to derail that effort, one of the last key goals of Obama's foreign policy.
He was invited by Speaker of the House John Boehner, one of Obama's leading Republican opponents, and he accepted with neither party informing the White House.
Obama and Netanyahu both insisted the traditional alliance
"My speech is not intended to show any disrespect to President Obama or the office that he holds. I have great respect for both," Netanyahu told thousands of activists at pro-Israel lobby AIPAC's annual conference.
"Israel and the United States agree that Iran shouldn't have nuclear weapons. But we disagree on the best way to prevent them from developing those weapons."
The pace of the negotiations to hammer out a deal to rein in Iran's suspected nuclear arms program in exchange for sanctions relief has gathered pace as a March 31 deadline nears.
Speaking just ahead of Netanyahu, Washington's ambassador to the United's address Nations Samantha Power sought to counter his opposition to the emerging deal with Tehran.
"The United States of America will not allow Iran to obtain a nuclear weapon, period," she said. And she insisted that Obama would stand by US allies "whether the negotiations collapse or produce a diplomatic solution that meets our bottom line."