United States President Barack Obama says the Washington is working closely with Israel to prevent Iran from becoming a nuclear power.
In an interview broadcast live on NBC, the president said he believed Israel had not yet decided how to deal with the issue, amid reports that Israel may strike Iran as early as spring.
Mr Obama said the aim was to resolve the crisis diplomatically, but no option was off the table.
"I've been very clear - we're going to do everything we can to prevent Iran from getting a nuclear weapon and creating a nuclear arms race in a volatile region," he told his interviewer.
A BBC correspondent in Washington says President Obama, in the interview, was eager to play down tensions between the US and Israel over suggestions Israel is preparing a military strike against Iran.
But, she says, behind the scenes Washington is deeply alarmed by reports that Israel may strike Iran as early as April.
That would not only drive up tensions in the Middle East but also increase oil prices, which could threaten a fragile global economy.