Iran has huge natural gas reserves that it could use to run power plants. Can you think of any reason why they would want to waste their money on nuclear energy? The Russians have told them flat out that their business model is bogus if the plants they are building there are for energy production alone.
Also, Iran is probably doing it's best to constrain supply from Iraq by sending people and money over the very porous border to blow up pipelines and other oil producing facilities. In a strictly robber baron capitalist sense, it makes perfect sense for them do so.