authorize api calls only from my application

I want the api calls to be made from the application (not specific to any user). In a normal MVC, I have done the following

public class ValidateReferrerAttribute : AuthorizeAttribute
    {
        public override void OnAuthorization(AuthorizationContext filterContext)
        {
            if (filterContext.HttpContext == null)
            {
                throw new System.Web.HttpException("No Http context, request not allowed.");
            }
            else
            {
                if (filterContext.HttpContext.Request.UrlReferrer == null)
                {
                    throw new System.Web.HttpException("Referrer information missing, request not allowed.");
                }
                else if (filterContext.HttpContext.Request.UrlReferrer.Host != filterContext.HttpContext.Request.Url.Host)
                {
                    throw new System.Web.HttpException(string.Format("Possible cross site request forgery attack, request sent from another site: {0}", filterContext.HttpContext.Request.UrlReferrer.Host));
                }
            }
        }
    }

I want use the same logic for api calls and I have started as below. But I am unable to implement the same if else condition as above. What should be written for api calls to have same logic as above.

public class ValidateApiReferrerAttribute : AuthorizeAttribute
    {
        public override void OnAuthorization(HttpActionContext actionContext)
        {
            if(actionContext == null)
            {

            }
            else
            {

            }
        }
    }