I think there are three problems here.
One is that our propaganda arm, the U.S. Information Agency, was dismantled after the Cold War. The State Department absorbed its remnants but often cannot carry out the core mission and maintain a pleasant diplomatic environment.
Two, the current interpretation of the Constitution is so strict that the U.S. cannot be seen to advocate one religion or creed over another. Thus, U.S. officials can't really participate in religious debates with crazy mullahs. I'm not even sure if U.S. officials can sponsor private parties to do so.
Third, there is great difficulty for U.S. officials to reach the Pakistani media. The problem is two-fold: one, I'm told Pakistani newsmen often won't report what Embassy officials tell them, simply as a matter of pride. Two, the low literacy level of Pakistanis means one can't simply post on a website or advertise in newspapers to reach a target audience.
One story I heard was that to propagate news about a reward for a criminal who took refuge in Pakistan the embassy was reduced to advertising on matchbooks. That actually worked.
