Which version of CRM you are using? You can call the actions through workflow in CRM 2015. It has been introduced in CRM 2015 update 1.
If you are using CRM 2013, you can create workflow activity that will call the action.
OrganizationRequest orgReq = new OrganizationRequest("new_EnquiryCreateProject");
orgReq["parameter"] = "If any parameter specify"; // You can have parameter of diffrenet type.. This is for string type.
orgReq["Target"] = new EntityReference("Entity Name", "GUID of record");
OrganizationResponse orgResponse = service.Execute(orgReq);