Which one is correct to say:
- I'm sorry for disturbing.
- I'm sorry for the disturbance", and why?
Is it mandatory to use gerund after prepositions or we can use it in its original noun form?
Thank you in advance.
You can use either. However, you have a grammatical error in your first example, and they mean different things.
I'm sorry for being disturbing.
I'm sorry for disturbing you.
This corrects the grammar issue. You can't just say disturbing on its own.
In this sentence, you are apologizing for being the cause of a disturbance.
I'm sorry for the disturbance.
Here, you are apologizing for a disturbance in general, one which you may or may not have caused. For instance, you could be apologizing for the loud noise of a train that has passed by your house where you live.
You could use either really,
I am sorry if you found x disturbing for y reason.
I am sorry if x caused you a disturbance.