Hi Slawek,
Welcome to
RP!
Looking at your picture, I think I understood what you meant by 'colour circles' .... If I'm not wrong that's called 'banding'...
To remove 'banding' I, usually, only add a bit of 'noise' but, in this picture, it didn't really work so, I did the following:
- Duplicated the Background Layer.
- Selected and feathered the background.
- Run a strong 'Motion Blur' on the selection.
- Added a bit of noise.