The United States still has a military presence in Iraq and could be instrumental in putting such a force in place, whether by direct participation or through the use of its support facilities. My own belief—and this is easy for me to say, because I'm not directly involved in making the decisions—is that even if a relatively small force of UN blue helmets were put in place, the Iraqi government would feel reluctant to undertake any kind of forcible action.
I can't speak for the Iranians—that's a whole different thing entirely. As was pointed out before, this is relatively close to the border, but I don't think the Iraqis would take on the entire international community by assaulting a UN force.