In this paper, a general 3-D model for K-tier heterogeneous networks (HetNets) is proposed to investigate the performances of device-to-device (D2D) communications in highrise centers. The new model is based on stochastic geometry, where a 3-D Mat'ern hard- core process (MHCP) is used to describe the different cells positions in the network with realistic constraints. We derive the expressions of average successful transmission probability (STP) for D2D and standard cellular (SC) communications with different well known interference management techniques. Monte Carlo simulations are conducted to evaluate the analytical results. These results confirm the accuracy of the proposed model which presents an efficient description and tractable model to evaluate the performance of dense small cells deployment in HetNets.