This paper deals with a class of nonsmooth interval-valued optimization problems (NIVOPs) whose objective and constraints are interval-valued functions (IVFs). For this, we propose a new concept of symmetric invexity (S-invexity) for IVFs based on gH-symmetrically derivative, and deduce a sufficient optimality condition for non-dominated solutions. Furthermore, we establish appropriate duality theorems for Wolfe and Mond-Weir type duals. Examples are also presented to illustrate corresponding results.