A data storage device is disclosed comprising a head actuated over a disk. A read signal from the head is sampled to generate signal samples, and the signal samples are filtered with an equalizer filter to generate equalized samples. The equalized samples are filtered with an inter-track interference (ITI) filter to generate ITI attenuated samples, and a data sequence is detected based on the ITI attenuated samples. In one embodiment, the ITI filter comprises a transfer function: 1−HPF(ek) and in another embodiment the ITI filter comprises a transfer function: 1−LPF(ek) where ek represents a noise sequence in the equalized samples, HPF represents a high pass filter operating on ek, and LPF represents a low pass filter operating on ek.