Meeting the Israeli leader at the White House, Mr Obama said a nuclear Iran would be an "unacceptable" development.
On Sunday, Mr Obama told a pro-Israel conference in Washington there had been too much "loose talk" of war with Iran.
Israel fears Iran is seeking to develop nuclear weapons, although Tehran insists its nuclear plans are peaceful.
"The bond between our two countries is unbreakable," Mr Obama said, as the two leaders sat side-by-side in the Oval Office.
The president emphasised: "We believe there is still a window that allows for a diplomatic resolution," but added that the US would consider "all options" in dealing with Iran.
Meanwhile, Mr Netanyahu said Israel "must have the ability to defend itself, by itself, against any threat". (+ videos) » | Monday, March 05, 2012
