Given that the magnetic field is non-uniform. The magnetic field will not be uniform throughout the area of the loop. Due to non-uniformity, the magnetic flux lines will be random. In random motion, the filed does not vary with time. If there is no change in the magnetic field, it can’t induce emf in the loop. So if the metallic loop is placed in a non-uniform magnetic field, the filed will not induce emf in it. Thus, Non-uniform magnetic field does not induce the emf.