Is it possible to filter users from a launchd plist?

Question

I have some launchd plists that are now placed at the administrator per-user level, particularly inside: - /Library/LaunchAgents OR - /Library/LaunchDaemons

I'd like to avoid that some of those services could start only for one user (possibly avoiding to move all the plists to ~/Library/LaunchAgents), which is the simplest way?

Thanks in advance.