US Secretary of State Hillary Clinton Friday backed a "peaceful" resolution of the nuclear row with Iran as she met Israeli Defense Minister Ehud Barak, whose nation has threatened pre-emptive military strikes against Tehran.

Standing next to Barak, Clinton told reporters the United States was working with its international partners to increase pressure on Iran -- a reference to fresh UN sanctions -- to "change course" in the dragging showdown.

Barak welcomed efforts by President Barack Obama and Clinton to seek "effective" sanctions against Iran while vowing not to lose sight of the possibility they may fail to work.

"We remain committed to a diplomatic peaceful resolution," Clinton told reporters before going into private talks with Barak.

But "Iran is not living up to its responsibilities and we are working with partners in the international community to increase pressure on Iran to change course," the chief US diplomat said.

She was referring to the report last week by Yukiya Amano, chief of the UN watchdog, the International Atomic Energy Agency (IAEA), who expressed concern Iran might be seeking to develop a nuclear warhead.

During a tour of Saudi Arabia and Qatar, just before Amano issued the blunt report to the IAEA board of governors, Clinton warned the evidence increasingly pointed to Iran's seeking a nuclear bomb.

She also feared Iran was heading toward a "military dictatorship" as she charged that the Republican Guards, which run Iran's nuclear and missile programs, were supplanting Iran's clerical and political leadership.

Barak gave qualified support to the US push for sanctions.

"We also highly appreciate the effort made by President Obama and the secretary to make sure that sanctions against Iran will become effective," Barak said.

But Israel will not lose "eye contact with the possibility that in spite of all effort, it will not lead to Iran accepting the international norms," the defense minister said.

On February 3, Israeli Strategic Affairs Minister Moshe Yaalon raised the possibility of using force to stop Iran from developing nuclear weapons, which the West suspects Tehran is seeking under cover of its civilian nuclear energy program. Iran denies the charges.

Yaalon also urged the international community to impose even harsher sanctions on Iran.

Tehran has already faced three successive rounds of UN sanctions for refusing to stop enriching uranium, a process that can produce fuel for nuclear reactors but also fissile material for an atomic bomb.

The United States is leading efforts to halt Iran's contested nuclear program among the so-called P5-plus-1 group of the five permanent veto-wielding members of the Security Council -- Britain, China, France, Russia and the United States -- plus Germany.

China has been reluctant to seek sanctions against Iran.

Clinton also made a fresh push to restart peace negotiations between Israel and the Palestinians, which came to an abrupt halt with Israel's military incursion into the Hamas-ruled Gaza Strip in December 2008.

The Obama administration is "deeply committed to a comprehensive peace beginning with a relaunch of meaningful negotiations between the Israelis and Palestinians as soon as possible," she said.

She also said she would discuss with Barak the need to improve the situation in Gaza, which is controlled by the extremist group Hamas, "while keeping in mind very real Israeli security concerns."

Barak said: "We understand that we'll have to take tough decisions while not losing eye contact with our security needs and making sure that both sides will be able to live in security and peace."