Hi Pedro,

unfortunately this action is not available in UDAs (I wonder why...). However you should be able to set item permissions using REST API.

Reference: http://spsite.pro/Blog/Post/3/SharePoint-2013-REST-API-%E2%80%93-How-to-set-Unique-Permissions-%28Item-Level-Permissions…

With the OOTB Permissions web service from SharePoint it is only possible to set list or site permissions but not on item level.

Let us know how this works for you.

Regards

Philipp