To be safe, mobile multi-robots systems need to be able to adapt to unexpected behaviours of robots as well as to exogenous changes in the environment. In this paper, we describe a novel approach for the development of multi-robots systems where robots collectively collaborate with each other to satisfy their goals and to adapt their behaviour in a collective way satisfying the overall system safety. Safety-specific self-adaptation capabilities of the approach are generic and independent from the functional behaviour of the robots. An example dealing with safety for autonomous UAV is provided as well.