"In our calculations, we aren't taking these claims very seriously because we see them as hollow and baseless," foreign ministry spokesperson Ramin Mehmanparast told reporters in a weekly briefing.
"Even if some officials in the illegitimate regime [Israel] want to carry out such a stupid action, there are those inside [the Israeli government] who won't allow it because they know they would suffer very severe consequences from such an act," he said.
Iran's defence minister, General Ahmad Vahidi, was quoted by the ISNA news agency saying that Israel "definitely doesn't have what it takes to endure Iran's might and will".
He called the Israeli threats "a sign of weakness" by "brainless leaders".
The comments were a response to bellicose rhetoric from Israeli Prime Minister Benjamin Netanyahu and Defence Minister Ehud Barak in recent days suggesting they were thinking more seriously of military action against Iranian nuclear facilities.
"We are determined to prevent Iran from becoming nuclear [armed], and all the options are on the table. When we say it, we mean it," Barak told Israeli radio last Thursday.
Israeli media have underlined the threat, reporting that a decision could be made within weeks. They have also highlighted opposition to the idea by current and former Israeli military officials.
The US has recently multiplied visits by top officials to Israel in what appears to be an attempt to dissuade the Jewish state from targeting the Islamic republic.
"We continue to believe there is time and space for diplomacy," White House spokesperson Jay Carney said on Monday.
Israel insists Iran is on the point of developing nuclear weapons and says it reserves the right to act to prevent that.
The Jewish state has in the past launched air strikes to destroy nuclear facilities in Iraq and, reportedly, in Syria to protect its own regional nuclear weapons monopoly, whose existence it refuses to officially confirm.
Iran says its nuclear programme is exclusively for peaceful, civilian uses.
In the past couple of years it has ramped up uranium enrichment to a level just a few steps short of military-grade fissile material, saying those stocks are needed to create medical isotopes. It has also refused UN nuclear inspectors access to suspect military installations.
Renewed negotiations between Iran and the five top UN Security Council powers, plus Germany, have taken place this year. They have been downgraded after it became clear they were in an impasse, but not ended.
In the meantime, Iran is suffering from increasingly tough US and EU economic sanctions that have crippled its all-important oil exports. – Sapa-AFP