We propose a coarse-grained simulation model for segment interactions of entangled polymers in a primitive chain network (PCN) model. We express interactions between two segments in a PCN by a pairwise Gaussian soft-core potential. We show that our pairwise interaction model can improve several properties at small length or short time scales. The short range parts of the radial distribution functions by our model are qualitatively different from one of the original PCN model, which implies the short-range effective repulsive interaction. Such a short-range repulsive interaction affects several statistical quantities. We also show that some properties seem to be rather unphysical, which may be due to artifacts of the model. We discuss origins for this problem and possible ways to improve the model.