I have submitted a sitemap.xml on one of my new websites and it gives the following error although my links do not have www. prefix

Can someone help me out:

Line:
4
Paths don't match
We've detected that you submitted your Sitemap using a URL path that includes the www prefix (for instance, http://www.example.com/sitemap.xml). However, the URLs listed inside your Sitemap don't use the www prefix (for instance, http://example.com/myfile.htm). [?]