The world needs to show the Iranians that their "non elected nutcase" will only bring problems to Iran. He uses the self created hostility to Iran as a rallying call for patriotism. He is playing to his Islamist constituency and using them to force his agenda on the rest. Oil is not going to last forever and you can't eat nukes. Exporting Jihadists is not a great way to earn foreign currency.
Fabius, visiting Tehran, invites Rohani to France (Reuters)
from the article: What to do with Ahmadinejad