Israeli Knesset (parliament) opposition chairman Shaul Mofaz on Wednesday slammed Prime Minister Benjamin Netanyahu, blaming him for causing unprecedented tensions with the U.S. government over a possible strike against Iran's nuclear facilities.

"Who are you trying to replace? The administration in Washington or that in Tehran?" Mofaz said at a special summer session of the legislature, according to the Ynet news site.

On Tuesday, speaking at a joint press conference with visiting Bulgarian Prime Minister Boyko Borisov, Netanyahu contended, "The world tells Israel 'wait, there's still time. And I say, 'Wait for what? Wait until when?' 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."

Mofaz, however, asked rhetorically, "Prime minister, please tell me who our biggest enemy is. The U.S. or Iran?"

Netanyahu has been actively trying to persuade the United States to draw "red lines" beyond which the Americans would act militarily to deter Iran from pursuing its nuclear ambitions.

However, the Obama administration has insisted that there is still "time and space" to pursue a two-track approach of sanctions and diplomacy to pressure Iran to give up its uranium enrichment activities.

Mofaz, however, referring to the Non-Aligned Movement summit, hosted in Tehran, said "We saw the results of Netanyahu's actions two weeks ago when 120 countries and the secretary-general of the United Nations applauded our greatest enemy."

But, Mofaz added, "The world will not turn its back on Israel," despite the gathering, adding "The world is not sick of Israel, the world is sick of Netanyahu and does not believe him."

On Monday, Clinton clarified that Washington is not currently prepared to publicly commit to laying down "red lines" for Iran.

Later on Tuesday, local media reported that Netanyahu would not meet Obama when he visits the United States later this month for the UN General Assembly in New York.

However, after an hour-long telephone conversation between Obama and Netanyahu later on, the two reiterated their determination to prevent Iran from acquiring nuclear weapons.

The White House said the two leaders discussed the threat posed by Iran's nuclear program, and bilateral cooperation on Iran and other security issues.

"President Obama and Prime Minister Netanyahu reaffirmed that they are united in their determination to prevent Iran from obtaining a nuclear weapon, and agreed to continue their close consultations going forward," the White House said in a statement.

The American officials denied that the Prime Minister's Office had requested to arrange a meeting between the two, or that they had turned down any such request.