This work is concerned with the reference tracking control problem for discrete-time Cyber-Physical Systems under denial-of-service (DoS) attacks. The physical process is modeled considering the presence of uncertainties, and an uncertain switched system is developed based on energy constraints in the behavior of the DoS attacker. Three different control strategies are addressed to mitigate the effects of the malicious agent, the use of a packet of different controllers, the application of a single fixed gain, and the possibility to set the input to zero during the attack. A numerical experiment is performed to illustrate the effectiveness of the proposed approach in following the desired reference signal, even with communication constraints.