What you can do is use URI Restrictions.

See: WordPress Dashboard s2Member (Pro) Restriction Options URI Restrictions (typical w/ BuddyPress)

That will allow you to define specific URIs that certain Membership Levels can access. For example, to require Level 1 to access /groups/ you would put /groups/ in the Level 1 field.

Tip: If you haven't already, I recommend watching the BuddyPress + s2Member tutorial video.