Israel's deputy defence minister has suggested that Israel could launch a military strike against Iran's nuclear programme as a "last resort".
Ahmadinejad has questioned the extent of the Holocaust many times
Ephraim Sneh told the Jerusalem Post he was not advocating action but "the last resort is sometimes the only resort."
Correspondents say the comments are the clearest yet on such a possibility from a senior Israeli official.
The Iranian president has regularly questioned the extent of the Holocaust, and been a trenchant critic of Israel.
In 2005 he drew widespread and angry international criticism when he approvingly quoted comments by Ayatollah Khomeini that Israel's existence should be brought to an end.
'Aware of repercussions'
The UN gave Iran an end of August deadline to stop enriching uranium, threatening sanctions if it did not.
Iran rejects Western allegations that its nuclear programme has a military aspect, and maintains it is enriching uranium only to generate electricity.
The Israeli politician told the newspaper he still hoped the international community would implement effective sanctions against the country.
"The chances are not high... My working assumption is that they won't succeed," he added.
"I am not advocating Israeli pre-emptive military action against Iran and I am aware of all of its possible repercussions," he said.
"I consider it a last resort. But even the last resort is sometimes the only resort."
A government spokeswoman said Mr Sneh's comments did not necessarily reflect the view of Israel's government or Prime Minister Ehud Olmert.