I've made a screenshot of my phone screen and imported it in Photoshop by dragging from disk. However it's clean "as-is" image of the phone screen, it has appeared in photoshop slightly blurred. How can I avoid this behavior? On the picture there are zoom of regular Preview mac os app on the left and Photoshop version on the right.
Actually your image in already blurred. If you save this photoshop file as a Jpeg. You'll find same result.
Don't worry about it. But if you want totally pixel free file then you have to remake the whole design.
And if you are confused about the blurred boxes then let me tell you that witj the help of these boxes you can do better editing in your image.