The person who's saying this sentence doesn't seem to show sorry to the listener but rather to seem to say that he/she must do what he/she was told to do. See the tense of the sentence. this person is not asking any forgiveness for what he/she has done in the pass but asking an excuse for what he/she is doing.(i am merely following orders.) That's why I don't see the person is really sorry for it.
so rather than 용서해주세요 (which is for asking mercy for seriously bad conduct or some sort), 죄송합니다 (which is nearly similar to 'excuse me') is better for this situation in my opinion.