Please post a sample at full size. This could just be a crop at full 1:1 size with no resampling. If you have a photo of a monitor/screen image, then this is likely moiré, best to get the original image file and not take a photo of a screen.
It depend what exactly you have as problem. In some cases maybe Spot Healing Brush can help while other times you will need lot of effort and skills. See suggestion above how to post/upload image so anyone can see it and give you more detailed and meaningful instructions.