Disrespectful means showing no proper regard for somebody. Talking over them, or treating what matters to them as a joke.
It takes to or towards, and it is a serious charge in most settings, since being disrespectful to a person's beliefs, culture or grief is worse than mere rudeness. Schools and workplaces use it as a formal category of behaviour. The noun is disrespect, which also works as a verb in informal speech, often shortened to dis. The positive form, respectful, is the word you want on a reference.
1adjectivedisrespectfulShowing a lack of proper regard for someone or something.
“It would be disrespectful to leave before the speeches.”
From dis- + respectful.
Etymology from Wiktionary, CC BY-SA