The United States insisted Monday there is still time for a diplomatic way out of the West's nuclear showdown with Iran despite a growing drumbeat of war in Israel.

The White House insisted that there remains a "window" for its strategy of pressure through punishing sanctions, adding that world power talks with Tehran could work despite the absence of a breakthrough so far.

"We continue to believe there is time and space for diplomacy, the opportunity remains for Iran to take advantage of this process," Carney told reporters on Air Force One.

Israeli Prime Minister Benjamin Netanyahu and Defense Minister Ehud Barak have stiffened their rhetoric on Iran, as President Barack Obama's re-election bid in high gear and aides keen to avoid sudden foreign policy crises.

In a possible reference to US conversations with the Netanyahu government, Carney said Washington had made it clear to its "partners" that there was sufficient time to convince Tehran to change course.

"There is every reason to continue the P5 plus one talks while the time and space remains," he said.

The P5 plus one process groups the permanent five members of the United Nations Security Council and Germany in painstaking negotiations with Iran.

Repeated rounds of talks have failed to end the standoff and Tehran has refused to make major concessions on its right to enrich uranium, a process used to make nuclear fuel but also the core of an atomic bomb.

The dispute between the Obama administration and the Netanyahu government on the state of Iran's nuclear program has been repeatedly been aired in coded statements from each side.

Israel wants to ensure Iran does not reach the "capability" to build nuclear weapons, in terms of the expertise, material and sufficient quantities of highly enriched weapons grade uranium to do so.

Obama has stressed that his position, reinforced by Carney on Monday, is that he will stop Iran from "acquiring nuclear weapons" a step further down the path to developing an atomic arsenal than the Israeli red line.

Carney's comments came as speculation in the Israeli press about a possible strike multiplied, with the newspaper Haaretz reporting top Israeli officials believe time is fast approaching for a decision by the Netanyahu government.

His remarks will further fan speculation over differences between Obama's White House and Netanyahu's government on the timing of any Iran operation.

Last week, in remarks seemingly aimed at Israel, the White House said it had "eyes" and "visibility" inside Iran's nuclear program and would know if Tehran made a "breakout" towards a nuclear weapon.

Washington also indicated it had not changed its view that Iran was not yet on the verge of building a nuclear bomb, despite Barak's claim last week that US intelligence now viewed the threat as more "urgent."

A stream of top US officials, including US Secretary of State Hillary Clinton and Defense Secretary Leon Panetta have visited Israel recently, amid speculation that Washington is trying to persuade Netanyahu not to strike.

Washington stresses that Obama has not taken the idea of US military action against Iran off the table. But Panetta said the United States should "exhaust every effort" before launching an attack.

There is concern in Washington that a unilateral Israeli strike may not destroy Iran's underground nuclear facilities, could spark Iranian retaliation worldwide and may drag the United States into another war in the Middle East.

The tension in Israel rose another notch on Sunday when the government began testing an SMS system to warn the public of any missile attack.

Netanyahu warned that all the threats facing Israel were "dwarfed by another threat -- different in both its scope and its essence. And so I repeat: Iran must never be allowed to get nuclear weapons."

Haaretz quoted an official familiar with a new intelligence report that said Iran had made recent progress recently in the "manufacture and assembly of a nuclear warhead."

Iran denies its nuclear program is geared towards producing nuclear weapons.

Pressure on Obama over Iran also increased last month when his Republican foe in November's election, Mitt Romney, visited Jerusalem and appeared to give his approval to Israel's red line on Iran's nuclear capability.

Obama argues that, with increased US and EU sanctions, Iran is under unprecedented heat and that its economy is suffering badly.

But US officials admit they are disappointed that this has yet to convince Iran to shift its position.