Networks-on-Chip (NoCs for short) are known as the most scalable and reliable on-chip communication architectures for multi-core SoCs with tens to hundreds IP cores. Proper mapping the IP cores on NoC tiles (or assigning threads to cores in chip multiprocessors) can reduce end-to-end delay and energy consumption. While almost all previous works on mapping consider higher priority for the application's flows with higher required bandwidth, a mapping strategy, presented in this paper, is introduced that considers multicast communication flows in addition to the normal unicast flows. To this end, multicast and unicast traffic flows are first characterized in terms of some new metrics which are then used for arranging communication flows based on their volume and priority. A heuristic approach is used to assign IP cores to NoC tiles. Simulation results for both synthetic and real applications show up to 49% (28% on average) performance improvement and 44% (22% on average) energy saving when compared to the best known mapping algorithm, nMap.