The normal term is speech community.
This has the advantage over "language community" in that it can be used for communities which don't speak a distinct language, but only a dialect, or some minor variant of the language.
The term is used to focus on identifiable communities of people with shared behaviours. In a context where two languages are in context, many speakers will be L1 speakers of one language and L2 speakers of another. Categorising people by the languages the know and speak is not likely to be very productive because of the overlaps. Instead distinct speech communities can be identified based on the languages they speak at home, in school, in the workplace, the languages they watch on TV etc.