Netanyahu, with U.S. Defense Secretary Leon Panetta at his side, told a news conference in Jerusalem the Iranian regime doesn't think the international community "has the will to stop its nuclear program," The Wall Street Journal reported.
"This must change, and it must change quickly because time to resolve this issue peacefully is running out," Netanyahu said.
U.S. officials have insisted the sanctions are having an impact and urged Israel to remain patient to give them more time to work.
During a briefing with reporters aboard Air Force One, however, White House spokesman Jay Carney admitting Wednesday the sanctions have yet to have the desired effect.
"They have not yet had their desired -- of course, if the sanctions had forced Iran to make the decision to live up to its international obligations, Iran would have made the choice that would have allowed them to rejoin the community of nations and obtain some relief from the sanctions," Carney said. "The purpose of the sanctions is to change Iranian behavior. Now, that change has not yet come. But that does not mean the sanctions are not having an effect on and an impact on the economy or on the regime."
Earlier, Panetta said Israel and the United States "have a strong bond, not only of friendship but of security."
Prior to meeting Israeli Defense Minister Ehud Barak in Tel Aviv, Panetta said the United States will do everything "to defend both our countries."
Iran and Syria are expected to top the agenda, unnamed Israeli officials told The Jerusalem Post.
Later, while visiting an Iron Dome missile defense system outside Ashkelon, Panetta indicated the United States is prepared to use military force to stop Iran's race for nuclear expertise.
"If they continue and if they proceed with a nuclear weapon ... we have options that we are prepared to implement to ensure that that does not happen," the Post quoted Panetta as saying.
"Ties between Israel and the U.S. in the security realm are as strong and close as they have ever been, and without a doubt, a substantial part of the credit belongs to Defense Secretary Leon Panetta. ... There are disagreements but this does not affect the profound depth of our ties and we plan to keep it that way," Barak said.