I would say it is, judging that embassies are considered foreign soil.
If you ask me, this might make sense on an operations level--investigating whether documents reveal any concrete evidence of Iranian involvement with the ongoing hostilities in Iraq--but on a PR level it is terrible. We announce we're sending in more troops, essentially rattle the saber at Iran and Syria, and then commit an act of war.
We can sit around all day and say they've had this coming to them, but knowing Iran, they'll play this up as much as they can, and frankly, as dirty as their hands are, we're the ones who have rushed to action here.
I think that we'll never win the PR war, since everybody loves to hate us, but I disagree that we rushed into action here.
It's not an embassy, but a consulate, and diplomatically speaking the difference is apparently significant.
Maybe there's something wrong with me, but I get a good, clean feeling from this.
In any case, regarding dirty hands, here's an interesting reference from Cap Huff:
Article 55
RESPECT FOR THE LAWS AND REGULATIONS OF THE RECEIVING STATE
1. Without prejudice to their privileges and immunities, it is the duty of all persons enjoying such privileges and immunities to respect the laws and regulations of the receiving State. They also have a duty not to interfere in the internal affairs of that State.
2. The consular premises shall not be used in any manner incompatible with the exercise of consular functions.
3. The provisions of paragraph 2 of this Article shall not exclude the possibility of offices of other institutions or agencies being installed in part of the building in which the consular premises are situated, provided that the premises assigned to them are separate from those used by the consular post. In that event, the said offices shall not, for the purposes of the present Convention, be considered to form part of the consular premises.