Not really. Webservices are like anything else you can put on the web:
When you don't want everyone in the world to access your data, don't put it
on a public website.
You could have your webservice check the users Referer-header and only serve requests which originate
from your website. But this header is optional and provided by the
user-agent, so it can be faked by illicit users or omitted by legitimate
users, so it's not a reliable way.
You could also have your webservice use authentication with username and
password. That would at least restrict access to registred users and allow
you to control which data each user can access. But it doesn't prevent
users with login credentials from accessing the webservice without your