In fact, we have not intervened.
Since you are against intervention, you actually agree with the way Obama has not intervened becuase he coudn't get Russian and Chinese permission.
Obama hasn't intervened in Syria for the same reason he hasn't bombed Iran. He's really not into military action, except for aspects he can't avoid without looking weak (which is why the drone strikes just keep on coming). I think he should have just bombed Iran. A nukeless Iran will deprive the Gulf kingdoms of any excuse to have their own nukes.