Doubt it. There is no credible evidence at all. It's fear mongering which is a traditional tactic to divert attention away from other issues, namely Operation Fast and Furious which was a historic failure of the government and ended up getting hundreds of Mexicans killed.
Don't believe any information obtained by the use of torture or sting operations, as is the case with the assassination "plot". There's already politicians pushing for a military response to Iran. Coincidentally, those are the same people who pushed for war in Iraq and have the most to gain from military actions in the region. It's all lies.