Sketchy backlinks appearing in SEMRush

Hi all, I’m by no means an SEO expert. I’m a bathroom fitter and have recently built a website in the hopes of getting to the top of google for “bathroom fitters” in my local area. I’ve been signing my business details up to some directories which have a good DA (according to keywords everywhere) and linked my website to a free version of SEM Rush to keep track. When I click on the SEM back links report, there appears to be some “suspicious” or “dangerous” backlinks appearing with my web address in there. These are definitely not websites I’ve signed up for. The report does say all of them are “no follow” Does this have any cause for concern? I’m aware there is a google tool to “disavow” these links. Should I do this or does the “no follow” mean that these backlinks are not looked at by google? Thanks