"September 11 denial", whatever that may mean, has nothing to do with Mr Ahmadinejad! Please care to search on e.g. YouTube (see, let us say, this page) and notice that there are Americans who are propounding conspiracy theories about the September 11 atrocity. Further, I should point out that during his one but last visit to the headquarters of the UN in New York, Mr Ahmadinejad asked to visit the location of Twin Towers (i.e. the Ground Zero), to pay respect to the dead, but the New York authorities declined his request, citing "security reasons" as their reason for declining the request. Be it as it may, to my best knowledge no one has ever denied September 11 happening, however there are some who question the official explanation as to who stood behind the event. It could be that Mr Ahmadinejad has also questioned the official explanation, but there is a world of difference between the denial of the official explanation and the denial of the event itself. Lastly, I should point out that there were also Iranians amongst the dead on September 11. In this connection, you may wish to search for the Iranian feature film The Ziggurat Goddess (about which here), 2004, with Shahab Hosseini in the main role. This film revolves around the life of a young Iranian man who has lost his wife and the only child in the September 11 atrocity, and in fact the film begins with the scenes of the attacks and contains flashbacks of the last telephone conversation that this man has had with his wife and daughter minutes before the first attack in which they were killed.