Answer 1
It is the policy of double standards adopted by the West. They want Israel to be the only dominating power in the Middle East.
US always supports Israel in UN by veto and UN can not have any limitation for Israel.
Answer 2
Iran is a country that has made clearly bellicose statements about how it would like to remake the Middle East. It has endorsed Hezbollah's violent attacks on the Lebanese Government, stalled progress in Syria by arming the vile Bashar al-Assad, threatened the Gulf Countries with violence, claimed a mandate to overthrow Bahrain's monarchy and liberate the Shiites of Bahrain and east Saudi Arabia, it has sent the Al-Kutz forces into Iraq to further inflame religious and ethnic tensions in Iraq, systematically and violently attacked the Balochi minority in the southwest and the Kurdish minority in the northeast, prevented the expression of Sunni Islam in its borders and violently attacked Sunnis gathering to pray - never mind the Baha'i, Yarsan, and Jewish minorities, repressed its own citizens in the Green Revolution of 2009 through violence and intimidation, and last but not least, has made clear that it wishes to remove Israel from the map.
Israel has done nothing even remotely similar. While the Occupation of Palestinian Territories is definitely problematic, it is not a crime or a threat on the order of magnitude of the Iranian crimes.
The West is quite reasonably afraid of a country like Iran acquiring nuclear missiles. This is the same reason why Western countries are opposed to North Korea having nuclear missiles.
Israel is the only nation in the Middle East known to have nuclear weapons.
For many Iranians, having nuclear power is a symbol of being a part of the developed world. They see the world preventing them from having nuclear weapons as part of a larger act of Europeans and Americans to prevent Iran from rising to be a first world country. They also consider it to be a question of double standards when Israel, India, and Pakistan are allowed nuclear weapons and nuclear power, but Iran is allowed neither.
Afghanistan has not argued that it wants nuclear weapons.
It doesn't look like Iran is trying to defend itself, Mahmoud Ahmadinejad is theatening to use nuclear weapons against Israel.
At this point in time (2012) Iran is believed to have no nuclear weapons capability at all. However this could end at any time (at which point Iran would be nuclear weapons capable).
No because they will just attack us.they already have to many nuclear weapons they dont need anymore.
because that makes them stronger and us weaker because we are not allowed to make them.
Israel has never made threats against Iran, while the Iranian government has made it very clear the destruction of Israel is their ultimate goal.
This is true for many reasons. First of all, Israel does not officially have nuclear weapons, although common international consensus is that they do. Secondly, Israel is a close ally of the United States, and any nation will be much quicker to condemn a nation that they fear (such as Iran) more so than a nation they trust. It is also much more accepted in the international community that Israel has nuclear weapons because it is a lone nation in a very hostile environment, and other nations that believe Israel may have nuclear weapons would think twice before attacking it. The United States knows that Israel would not dare using it's own nuclear weapons without the permission from either the US or the international community. On the subject of Iran, the international community has no reason to believe that Iran is pursuing nuclear capabilities for peaceful means. These reasons range from the fact that Iran has rejected to be provided with nuclear energy in exchange for giving up it's nuclear program, to the extreme aggressiveness of its current leader, Ahmadinejad (he has made numerous statements to other countries in which they should prepare for the complete and utter destruction of the United States, and Israel).
Russia, Iran, China, UK, US, Pakistan, North Korea and Israel, France, and India
America is opposed to Iran having nuclear weapons because we see their country as unstable and if they were allowed to have nuclear weapon capability they would either use it against us or sell them to radical terrorist group. At least that's what we believe.
Australia's view about Iran having nuclear , Australia does not support that because If Iran had their Nuclear weapons they will threat the world, and will cause an nuclear race in the Arab nations witch will lead to WW3