Let V be a locally finite, connected and weighted graph. We study non-existence results of non-trivial, non-negative solutions of the system {utt−Δu≥h1∣v∣p in V×(0,∞),vtt−Δv≥h2∣u∣q in V×(0,∞),u=u0;v=v0 in V×{0},ut=u1;vt=v1 in V×{0}, where p,q>1, h1,h2 are positive potentials. Under some volume growth condition of a ball, we prove that the system has no non-trivial non-negative solutions. In particular, our result is a natural extension of that in [D. D. Monticelli, F. Punzo, and J. Somaglia. Nonexistence results for the semilinear wave equation on graphs. arXiv.2506.08697, 2025.] from a single inequality to a system.