% sudo vi /etc/init/avahi-daemon.conf
-start on (filesystem and started dbus)
+start on (never and filesystem and started dbus)
stop on stopping dbus

One more thing to do in order to avoid the popup notice:

% sudo vi /etc/default/avahi-daemon
AVAHI_DAEMON_DETECT_LOCAL=0

To stop the daemon from the command line:

% sudo service avahi-daemon stop

And then, find out if it is really gone:

% ps -ef | grep -i [a]vahi

If you get no match, then it means that it is gone for good.

Full article.