I do not think there is

mremond — Sun, 12 Jul 2015 20:30:14 +0000

I do not think there is something standard in the XEP-0045 Multi-User Chat to search for room names.

Thus, I think you need to find a way to add the search either as an ejabberd plugin, or by another mean.

ejabberd - Comments for "Searching through room names"