This paper proposes an original interval-based method to compute an outer approximation of all invariant sets (such as limit cycles) of a continuous-time non-linear dynamic system which are included inside a prior set of the state space. Contrary to all other existing approaches, our method has the following properties: (i) it is guaranteed (a solution cannot be lost), (ii) it is applicable to a large class of systems without any specific assumption such as the knowledge of a Lyapunov function or any partial linearity, and (iii) there is no need to integrate the system.