Robotic swarms are usually designed in a bottom-up way, which can make robotic swarms vulnerable to environmental impact. It is particularly true for the widely used control mode of robotic swarms, where it is often the case that neither the correctness of the swarming tasks at the macro level nor the safety of the interaction among agents at the micro level can be guaranteed. To ensure that the behaviors are safe at runtime, it is necessary to take into account the property guard approaches for robotic swarms in uncertain environments. Runtime enforcement is an approach which can guarantee the given properties in system execution and has no scalability issue. Although some runtime enforcement methods have been studied and applied in different domains, they cannot effectively solve the problem of property enforcement on robotic swarm tasks at present. In this paper, an enforcement method is proposed on swarms which should satisfy multi-level properties in uncertain environments. We introduce a macro-micro property enforcing framework with the notion of agent shields and a discrete-time enforcing mechanism called D-time enforcing. To realize this method, a domain specification language and the corresponding enforcer synthesis algorithms are developed. We then apply the approach to enforce the properties of the simulated robotic swarm in the robotflocksim platform. We evaluate and show the effectiveness of the method with experiments on specific unmanned aerial vehicle swarm tasks.