Although I am nowhere near so frightened about Iran eventually getting a nuclear weapon as almost everybody else feigns to be, there is little question that the Iranian regime knows how to push buttons and create tensions. The problem from the U.S./West perspective is that there are no good options. People thrust their chests out and say Israel will bomb them, but not only would Israel have to cross Iraqi airspace (which would mean explicit U.S. approval/cooperation), there's little likelihood that it would locate and damage all or even most of Iran's secret nuclear facilities. If the Iranians have any ambivalence -- several Iranian experts I talked to said it was quite possible they're enriching right up to the point of having the components of a bomb that they could then finish like a "turnkey" operation whenever they decided, but might not build it as soon as it was technologically possible, rather wait until a propitious moment to announce it. Diplomacy might work, but it's hardly guaranteed and would take a long time.
So the feel-good option of imposing economic sanctions is the fallback position. But such sanctions seldom harm the regime that inspired them; indeed, they're more likely to hurt the people who are already oppressed but reinforce the rulers' power. And besides the fact that China is likely to cast a Security Council veto and Russia is hardoly a sure thing, it shouldn't be hard for Iran to beat a sanctions regime with smuggling, probably fuirther enrichjing the Revolutionary Guard along the way.
Perhaps the best choice is to quit meddling and quit paying attention to Ahmadinejad's rants?