"This version of Lync has been blocked by your system administrator. Please check for updates or contact your Lync support team."
To resolve above issue you have to install latest Lync 2013 update. So make sure you install Lync 2013 cumulative update released in July 2013.
Download Lync 2013 Cumulative update
To install the cumulative update open the following downloaded file,
Install-CsDatabase -ConfiguredDatabases -SqlServerFqdn SE.FQDN -Verbose