Avi is just a container format, and there are many different video codecs that can be used within them. Most dvd players that can play avi files need either xvid or divx video codecs in the avi file. And of course, many dvd players cannot playback avi files at all. You need to look at your player's manual to see if it can.
If you have iDVD, you can convert the avi to dvd-video format.
I'm not a Mac user, so I'm of limited help here.