Often suffering from under-optimization, Networkson-Chip (NoCs) heavily impact the efficiency of domain-specific Systems-on-Chip. To cope with this issue, heterogeneous NoCs are promising alternatives. Nevertheless, the design of optimized NoCs satisfying multiple performance objectives is extremely challenging and requires significant expertise. Prior works failed to combine many objectives or required an extended design space exploration time. In this paper, we propose an approach based on generative artificial intelligence to help pruning complex design spaces for heterogeneous NoCs, according to configurable performance objectives. This is made possible by the ability of Generative Adversarial Networks to learn and generate relevant design candidates for the target NoCs. The speed and flexibility of our solution enable a fast generation of optimized NoCs that fit users' expectations. Through some experiments, we show how to obtain competitive NoC designs reducing the power consumption with no communication performance or area penalty compared to a given conventional NoC design.