@Stack reader's answer is on the spot. I would just like to add an appendage.
As you have no doubt learned, the 'to be' verb in Japanese is です。Additionally, as you have noted, and @stack reader clarified, する is 'to do'. You can, however, use です with 失礼, but you need to be careful, or you'll end up sounding like a 外人 very quickly.
Is it rude if I ____?
A good rule of thumb here is that you use する whenever you are talking about a person, including yourself. If you are talking about a situation or action, there are times when you could use the 'to be' verb, です and be grammatically correct. The best way to learn the nuances of when to use です or する is to spend time speaking with a Japanese person, and frequently ask them to correct grammatical errors. Pay attention to what they say, as the best language teachers are the people you interact with regularly.
In short, people DO rude. 人間は失礼します。Things (including actions) ARE rude. 状態や行動は失礼です。Just watch out for the nuances of using です in place of する。