Kibana itself doesn't support authentication or restricting access to dashboards.

Currently I have proposal the following workarounds:
1. You can restrict access to Kibana 4 using nginx as a proxy in front of Kibana as described here: http://serverfault.com/a/345244. Just set proxy_pass to port 5601 and disable this port on firewall for others. This will completly enable or disable Kibana.
2. Elastic has a tool called Shield which enables you to manage security of elasticsearch. With Shield you can for example allow someone to analyze data in specific indexes with read-only permissions. https://www.elastic.co/products/shield

Please add support for this feature.