For restricting access to Confluence spaces so that a user/group may only view certain content.

Step-by-step guide

1. Create a new group in the Users or Global Users (if this is a JIRA + Confluence installation) administration page (For Cloud, see Create and update groups, and for Server, see Confluence Groups for Administrators).

2. In the Global Permissions Overview Confluence admin page provide that group with 'Can Use' permission along with any other permissions you'd like.
    

   For Cloud, you will need to add the group  to Confluence via User Management > Application Access > View Configuration. See Manage group access for more information.

   
   
   

3. In each space permissions page (1 page per space you wish the user/group to have access to) add the group to the permission with the appropriate level of access.
4. Finally, make sure users you wish to restrict are only part of the group you've just setup.

Related articles

(Archived) How to limit or restrict a user's project access in Jira server (for JIRA)