"Obviously, we don't want Iran to become a nuclear weapons power, but we are not planning anything other than going for sanctions," she told al-Arabiya television.
"What we are focusing on is trying to change Iranian behavior, and the international community has been united in trying to send a message to Iran that it is time for it to clarify its intentions," she said.
"We want to try to get the strongest sanctions we can out of the United Nations Security Council ... mostly to influence their decision-making," said Clinton, interviewed in Jeddah, Saudi Arabia on Tuesday at the end of a Gulf tour.
On Israel's refusal to rule out the military option against its arch-foe Iran, which denies charges of aiming to build a nuclear bomb, she said "there are many countries in the region who are very worried about Iran's actions.
"And there may well be those who think, well, we have to do something to protect ourselves," said Clinton,
But Washington believes "the better approach is to join at the international community, to work together toward sanctions, to exert maximum pressure on the Iranians, and to try every way we can to change their thinking."
Mullen not ruling out military action
Meanwhile, Admiral Mike Mullen, the chairman of the US Joint Chiefs of Staff, said in the Jordanian capital on Tuesday that Washington has not ruled out military action.
"The priority for President (Barack) Obama and his administration has been to initiate a dialogue and engagement while at the same time keeping all options on the table," he said.
"When I say all options are on the table it certainly includes potential military options," Mullen said.
Clinton, spelt out the failure of the Obama administration to engage with the Islamic republic, which has already defied three sets of UN sanctions by refusing to suspend its uranium enrichment.
"When President Obama came in, he was very clear that he wanted to engage, and that's what he's been trying to do – reaching out to the Iranian people, reaching out to the Iranian leadership," she said.
"And you have to ask yourself, why, when so many experts thought that there would be a positive response to President Obama's outreach, has there not?"
The secretary of state said the answer was that Tehran was increasingly coming under the control of the elite Revolutionary Guards at the expense of its clerical and political leadership
Clinton said the option of strong sanctions, targeting in particular the Revolutionary Guards, was the chosen path.
"It is our assessment that there is an opportunity still to try to convince Iran not to pursue nuclear weapons. And we've tried engagement, we've tried persuasion, we've tried fact-based argument," she said.