Couldn't the title of your post be; 'US supports attacks on Iran'
Frankly, no, since the US reprsentative denies it and there is no proof of it, only a Iranian claim.
The Iraqi army can't seal the border against insurgents and arms crossing from Iran, so it has to be a po faced hypocritical Iranian politician complaining they should seal it the other way up north.
I'm sure the US forces would just love to have them cross the border. Which makes you wonder if one side or the other, or both, is trying to provoke a casus bellum.