No.
You are correct in that this is not related to Copyright. Copyright is meant to protect expressions of an idea.
An URL is simply an address, like a street address. Can you legally stop people referring to your home address? No. Can you legally stop people from passing by and looking at your house on the street? Also no.
A famous case related to hyperlink is [Ticketmaster v Tickets.com (2000)][1]Ticketmaster v Tickets.com (2000). Tickets.com used information Ticketmaster's website and deep-linked to there. The ruling established that:
- use of information is not infringing
- hyperlinking cannot be copyright infringement because no copying is involved.
- deep linking is not unfair competition
If you feel that it is necessary to avoid people linking to specific pages of your site, you may consider accomplishing this technically. [1]:
UPDATE
It does not matter whether your site is meant to be public or not. For example, an knowledge base meant to be shared internally in an organization, but accessible on the internet since staff are geographically distributed.
Again, you may think of it like a street address. A private corporate building meant for employees only. An address, like http://en.wikipedia.org/wiki/Ticketmaster_Corp._v._Tickets.com,_IncRoom C, 16/F, Example Corporate Complex, 4321 Lucky Avenue can be shared like any other address. You cannot demand people to never refer to your office address. You can, however, setup a security post at the entrance and only allow certain guests to visit you.
In the case of a website, you may state in your terms that one cannot share access information to any external parties. This will include the sharing of any authentication data (e.g. password) which can be used to access content.