Ties between the United States and Israel showed new signs of strain on Tuesday, after Netanyahu blasted the US for not taking a harder line on Iran.
The White House, for its part, denied an Israeli source's claim that President Barack Obama had refused Netanyahu's request for a meeting later this month during the UN General Assembly.
"The president arrives in New York for the UN on Monday, September 24th, and departs on Tuesday, September 25th," said National Security Council spokesman Tommy Vietor. "The prime minister doesn't arrive in New York until later in the week. They're simply not in the city at the same time.
An Israeli official earlier told Reuters on condition of anonymity that Netanyahu's aides had asked for a meeting and "the White House has got back to us and said it appears a meeting is not possible. It said that the president's schedule will not permit that."
The White House said Netanyahu had not requested a meeting.
Netanyahu, who has met Obama on all his US trips since 2009, has been pushing him to adopt a tougher line against Iran.
He argues that setting a clear boundary for Iran's uranium enrichment activities and imposing stronger economic sanctions could deter Tehran from developing its nuclear program.
In comments that appeared to bring the possibility of an Israeli attack on Iran closer, Netanyahu had earlier taken Washington to task for rebuffing his call to set a "red line" for Iran's nuclear program.
"The world tells Israel 'Wait, there's still time'. And I say, 'Wait for what? Wait until when?'" Netanyahu said Tuesday, speaking in English.
"Those in the international community who refuse to put red lines before Iran don't have a moral right to place a red light before Israel," he added, addressing a news conference with Bulgaria's prime minister.
The website of Israel's daily newspaper Haaretz called his words "an unprecedented verbal attack on the US government."
Iran makes no secret of its hostility to Israel, widely assumed to be the region's only nuclear-armed power, but says its nuclear program is purely peaceful.
Netanyahu's relations with Obama have been strained over Iran and other issues, such as Jewish settlement building in the occupied West Bank.
But he has never framed his differences with Obama -- who has pledged he will "always have Israel's back" and is deep in a re-election campaign -- in moral terms.
Republican challenger Mitt Romney has accused Obama of throwing Israel "under the bus."
Netanyahu's comments followed US Secretary of State Hillary Clinton's remarks on Monday that the United States would not set a deadline in further talks with Iran, and that there was still time for diplomacy to work.
Netanyahu did not mention Clinton by name but pointedly parroted her use of the word "deadline," saying, "The sanctions have hurt the Iranian economy but they haven't stopped the Iranian nuclear program."
Israel had intensified war rhetoric against Iran but over the past week, he, in calling for a red line, had appeared to be backing away from military action and preparing the ground for a possible meeting with Obama.
Opinion polls suggest that a majority of both Americans and Israelis do not want war with Iran.