"Israel is not leading the struggle. Of course we exchange intelligence, we exchange views, we discuss issues, but it's not that we are planning any military attack on Iran," Sharon told CNN.
"Of course we take all precautions and all the steps to defend ourselves. But it's not that Israel should give the answer to the international problem," Sharon told Fox News in a separate interview.
Widely thought to be the Middle East's only nuclear power, Israel sent jets to bomb the Iraqi reactor at Osiraq in 1981, driving Saddam Hussein's quest for the bomb underground.
That attack has fuelled recent speculation that Israel might attack Iran.
Unhappy with European-led diplomatic efforts to win Iranian agreement to curb uranium enrichment - which can be used to produce nuclear arms - Israel has called for UN sanctions.
Sharon discussed "Iran's nuclear threat" in Washington talks with Vice-President Dick Cheney on Tuesday, a senior Israeli official said. The prime minister also raised the issue with President George Bush at his Texas ranch on Monday.
Sharon (L) discussed Iran with
Bush on Monday
Iran, which has called for Israel's destruction, says it has no interest in the bomb and wants nuclear power plants to meet booming demand for electricity.
Tehran has frozen its enrichment programme but refuses to relinquish permanently what it sees as a sovereign right to produce low-enriched uranium fuel for nuclear power plants.
"There is a time limit because Iran will soon reach a technological point of no return," the Israeli official said.
"We are not talking about when Iran actually produces nuclear weapons, but when it has the technological ability to do so.
"There has to be immediate action taken against Iran," he said. "We have to take this to the UN Security Council. They are the only ones with the tools to deal with this."
Independent experts have voiced doubts that Israel or the United States could mount an Osiraq-style strike on Iran, where the nuclear facilities are dispersed and fortified.
Sharon told CNN he was proud he was a decision-maker in Israel at the time of its 1981 strike on Iraq's Osiraq reactor but said the problem was not the same in Iran.
"Here the situation is different. The problem is different and much wider," he said, arguing that an international coalition should work to end Iran's nuclear programme.
In a report on Wednesday, The New York Times quoted US officials as saying Sharon gave Bush aerial photographs of sites in Iran and urged him to step up pressure on the Islamic republic to give up its nuclear programme.
"We have evidence that Iran makes every effort to possess nuclear weapons"
Israeli prime minister
According to the paper, Sharon argued that European nations negotiating with Iran were softening their position and may be willing to allow it to keep technology to enrich uranium.
The Times said US officials interpreted Sharon's evidence differently and think any Iranian nuclear weapons are likely to be several years away.
"We have evidence that Iran makes every effort to possess nuclear weapons," Sharon told CNN, but did not elaborate.
The Israeli leader was to fly home later on Wednesday, ending a four-day visit clouded by differences with Bush over Jewish settlement growth on land Palestinians want for a state in the West Bank.
But the prime minister, who won praise from the president for Israel's planned pullout from the Gaza Strip this summer, insisted in remarks to reporters that there was no crisis with the US over the West Bank settlement issue.