hyundai getz 1.3 only accept 100 RON fuel

I recently bought a hyundai getz 1.3 petrol car and its only "accept" a 100 RON fuel.
I have tried 95 RON whitch is the most common fuel in my country and the check engine lights up. If the tank is fully empty and i use 100 RON there is no problem anymore.

Is there something i can do to be able to use 95 RON fuel?
In my country it is much cheaper and i do not think this car should use 100 RON petrol.