Recently, generalized frequency division multiplexing (GFDM) is a multicarrier 5G waveform candidate for flexibility of its pulse shaping filters. However, the flexible pulse shaping filters may result in inter carrier interference (ICI) and inter symbol interference (ISI), which become more severe in a broadband channel. In this paper, for the elimination of the ISI and ICI, based on discrete Gabor transform (DGT), a transmit GFDM signal is first treated as an inverse DGT (IDGT), and then a frequency-domain DGT is proposed to recover the GFDM signal at the receiver. Furthermore, for the complexity reduction, a suboptimal frequency-domain DGT called local DGT (LDGT) is developed. Theoretical analyses and simulation results show that the proposed DGT can obtain promising bit-to-error rate (BER) performance with low complexity.