In this paper, to suppress jamming in the complex electromagnetic environment, we propose a joint transmit waveform and receive filter design framework for integrated sensing and communications (ISAC). By jointly optimizing the transmit waveform and receive filters, we aim at minimizing the multiuser interference (MUI), subject to the constraints of the target mainlobe, jamming mainlobe and peak sidelobe level of the receive filter output as well as the transmit power of the ISAC base station. We propose two schemes to solve the problem, including joint transmit waveform and matched filter design (JTMD) and joint transmit waveform and mismatched filter design (JTMMD) schemes. For both schemes, we adopt the alternating direction method of multipliers to iteratively optimize the transmit waveform and receive filters, where the number of targets as well as the range and angles of each target can also be estimated. Simulation results show that both the JTMD and JTMMD schemes achieve superior performance in terms of communication MUI and radar detection performance.