The concept is possible, although there are a few problems:
- The drone/access point must be visible above the horizon for anyone that wants to use it. That means that it has to be inside Iran, and I doubt the Iranian Air Force would ignore it.
- The low power levels typically used in WiFi would require users to move outside, onto the roof, etc. It wouldn't work well from inside a building, or under trees.
- The number of users in a typical metropolitan area would overwhelm a single drone overflying it by trying to transmit to it simultaneously and interfering with each other's uplink. It could be used for broadcast (i.e. Multicast), but there are already efficient ways to broadcast information.
There are a few companies developing drones specifically designed to fly at high altitude and provide Internet access to sparsely populated areas, but I wasn't able to find a URL quickly and I'm not aware of anyone that has actually deployed it.
But, the concept has been around for quite a while -- it's not an original thought.