Edit in JSFiddle

var app = angular.module('app', []);

app.controller('appController', function ($scope) {});

app.directive('classDirective', function () {
    return {
        restrict: 'C',
        transclude: true,
        template: '<div class="target">classDirective example - <span ng-transclude></span></div>'
    };
});

<section ng-app="app" class="container">
    <section ng-controller="appController">
        <div class="not-target classDirective">text</div>
    </section>
</section>

.target {
    width: 100px;
    height: 100px;
    border-radius: 5%;
    margin: 30px;
    padding: 20px;
    background: #00a;
    text-align: center;
    color: #fff;
}