Some people may wonder why would the US reveal such information to anyone. With regards to the news people, all you need to think of is how the major news networks all just 'so happen' to have people on site whenever a major offensive is started. As for foreign governments, it's merely a matter of courtesy, so that they can get things in place to get their own people out speedily. So, you need to wonder why the attack was 'called off' this time [if this rumour was true in the first place-Ed].
Well, I don't know the reason why, but I'm guessing that the timing of the capture and the release of UK service personnel might have had something to do with it. Iran scored a major PR victory in that round of contest. It would look extremely bad on the US if they chose to whack them days after their 'gift' to the British people.
Some people have suggested that the capture of the personnel was deliberate, that they allowed themselves to be captured, in order to create a pre-text for war. Personally, I do not believe that the British would be so stupid. The US has shown (in Iraq) that it doesn't need any real reason to attack anyone. So, it doesn't make sense to sacrifice 15 personnel for no reason.
Although I hope that no more shooting wars are started, something just doesn't feel right when the US has got two carrier groups in that small stretch of water. So, if you ask me, I personally think that the attack has just been postponed for the time being. It certainly has not been taken off the table as yet. You don't steam carrier groups to the gulf if you don't intend to use them.
UPDATE: Haliburton has just announced that they've finished all their business in Iran and are done. They have stopped taking new contracts since January and have finished up all their current business. I wonder if this is a signal.