Benjamin Netanyahu, Israel's prime minister, has bluntly told Barack Obama that he would never compromise on his country's security even as the US president sought to reassure him on nuclear diplomacy towards Iran and pressure him on Middle East peace talks.

In a White House meeting on Monday, overshadowed by the Ukraine crisis, the two leaders avoided any direct clash during a brief press appearance but were unable to paper over differences on a pair of sensitive diplomatic drives that have stoked tensions between them.

It's my belief that ultimately it is still possible to create two states, but it's difficult and it requires compromise on all sides Barack Obama, US president

Obama assured Netanyahu of his absolute commitment to preventing Iran from developing atomic weapons, despite the Israeli leader's deep scepticism over US-led efforts to reach a final international deal to curb Tehran's nuclear programme, the Reuters news agency reported.

But, warning that time was running out, Obama also urged Netanyahu to make tough decisions to help salvage a faltering US-brokered peace process aimed at reaching a framework agreement with the Palestinians and extending talks beyond an April target date for an elusive final accord.

"The Israeli people expect me to stand strong against criticism and pressure," Netanyahu told the president.

Obama and Netanyahu, who have had strained relations in the past, showed no outright tension as they sat side-by-side in the Oval Office, Reuters reported.

Netanyahu arrived in Washington to a veiled warning from Obama that it would be harder to protect Israel against efforts to isolate it internationally if peace efforts failed.

"Iran calls openly for Israel's destruction, so I'm sure you'll appreciate that Israel cannot permit such a state to have the ability to make atomic bombs to achieve that goal," Netanyahu said. "And I, as the prime minister of Israel, will do whatever I must do to defend the Jewish state."

Obama is seeking room for diplomacy with Iran, while Netanyahu, who has stoked US concern in the past with threats of unilateral strikes on Iran's nuclear sites, has complained that sanctions on Tehran are being eased prematurely.

The meeting with Netanyahu marked a new direct foray into Middle East peacemaking by Obama, whose first-term efforts ended in failure.

'Compromise on all sides'

"Israel has been doing its part, and I regret to say that the Palestinians haven't," Netanyahu said, an assertion he is likely to repeat on Tuesday to the pro-Israel lobbying group AIPAC, a past podium for some of his most strident speeches.

Obama commended Netanyahu for his role in the talks that resumed in July but "warned that the timeframe that we have set up for completing these negotiations is coming near."

"It's my belief that ultimately it is still possible to create two states," he said. "But it's difficult and it requires compromise on all sides."

Palestinians point to Israeli settlement-building in occupied West Bank territory as the main obstacle to peace.

Netanyahu told Obama that Jewish history taught Israelis that the best way to guarantee peace is to be strong.

The Israeli prime minister used their brief joint appearance to put the onus on the Palestinians to advance prospects for peace and also to vow to hold the line on what he sees as Israel's security imperative.

His remark harkened, but without the stridency, to an Oval Office visit in 2011 when he famously lectured the US president on the long struggles of the Jewish people, as he sought to counter Obama's call to base any peace agreement on borders that existed before the 1967 Middle East war.

Ukraine shadow

Ukraine has dominated Obama's agenda. "I know you've got a few other pressing matters on your plate," Netanyahu joked to Obama, who used his press appearance to warn Russian President Vladimir Putin that Moscow faces international isolation for its military intervention in Ukraine's Crimea region.

On Iran, Obama and Netanyahu gave no real sign of progress in bridging fundamental differences, Reuters reported.

Netanyahu, whose country is the Middle East's only, if undeclared, nuclear-armed nation, has denounced as a historic mistake an interim deal that world powers reached with Iran in November, under which it agreed to curb sensitive nuclear activities in return for limited sanctions relief.

He has insisted that any final deal must completely dismantle Tehran's uranium enrichment centrifuges, a position that is at odds with Obama's suggestion that Iran, which says its nuclear programme is peaceful, could be allowed to enrich on a limited basis for civilian purposes.