but a 20 KG satellite can have some military applications, but that's unlikely for a first satellite attempt. Microsats and nanosats are getting a lot of attention because their capabilities are increasing as the technology improves. Systems that used to weigh many kilograms can now be built that only weigh a few grams and use a fraction of the electricity of the old systems. GPS navigation has been tested in space that allows for high precision maneuvering, along with things like LIDAR for rendevous. The smaller you can go, the less propellant is required for a given amount of Delta-V. You don't necessarily have to physically damage a satellite to mess with it. There are other ways that I really don't care to discuss that are a lot more subtle. China is said to be working on such microsat and nanosat weapons technology.

Still, the chances of intercepting a specific satellite are very slim unless you can launch into a compatable orbit. That may or may not be possible from Iran due to range constraints (not wanting to overfly hostile neighbors). That's why Israel's Offek satellites are launched into a highly retrograde orbit - any other launch azimuth would overfly neighbors and perhaps be intrepreted as a warlike act. Photographic imagery satellites are usually in slightly retrograde (about 96-98 degrees) sun-sunchronous orbits. Radar imagery satellites will typically be in polar or high inclination orbits to cover the greatest amount of land area. Without knowing their launch site or the range constraints, I couldn't say if an Iranian satellite could be launched into a compatible orbit. Even if you're planning on using detonation or a kinetic intercept, there is a limited range of orbits that you can launch into and still have a reasonable chance of a hit.