This post, where you have added a comment, contains a lot of suggestions on how to improve a project with the issue you described: https://community.pix4d.com/t/4415
First, I would try to modify the minimum number of matches, this should already remove some noise:
Then, the post cited above also mentioned that improving the image acquisition improved the results, e.g. by adding oblique images and by flying lower.
Adding Manual Tie Points (MTPs) can help as well: https://support.pix4d.com/hc/en-us/articles/202560349
Or adding surfaces to smooth the DSM: https://support.pix4d.com/hc/en-us/articles/202560449
Could you share screenshots of your project? if possible, also the quality report (click Process > Generate Quality Report). This helps to understand the settings of the project.
Let us know if the suggestions above could improve the project.