Phase extraction in differential synthetic aperture radar (SAR) interferometry (DInSAR) is an important tool used for detecting subcentimeter-level change in ground deformation. The evaluated phase map processing is conducted via two important and successive steps: phase denoising and phase unwrapping. We attack the first step and propose the performance of discrete Riesz wavelets transform to reduce the residual speckle noise from the generated DinSAR phase map. The performance of the proposed method is appraised using three important criteria such as peak-to-signal-noise ratio (PSNR), the quality index Q, and the edge preservation index. The obtained metric values reveal that this technique can improve the PSNR and Q in comparison with other famous techniques. Finally, we apply the algorithm to denoise a real DinSAR phase map generated with sentinel application platform software using three SAR data of the Napa city in California.