add_action( 'woocommerce_after_shop_loop_item', 'add_attr_catalog', 3 );

function add_attr_catalog() {
    global $product;
    $attributes = $product->get_attributes();

    foreach ($attributes as $attribute) {
         //print_r($attribute);
         $attr_name =  substr($attribute['name'], 3);
         $attr_value = $attribute['value'];
         $attr_nice_name = get_attr_name($attr_name);
         if (!empty($attr_value)) {
            if ($attr_name == "vysota-matrasa-sm") {
                echo '<p class = "attr_in_loop">Высота матраса: ' . $attr_value . ' см</p>';
            }
            else {
                echo '<p class = "attr_in_loop">' . $attr_nice_name . ': ' . $attr_value . '</p>';
            }

         }
    }
}

function get_attr_name($attr_slug) {
    global $wpdb;
    $query = $wpdb->get_results("SELECT `attribute_label` FROM wp_woocommerce_attribute_taxonomies WHERE `attribute_name` = '$attr_slug';", ARRAY_A);
    return $query[0]['attribute_label'];
}