<?php if (have_posts()) : ?>
<?php while(have_posts()): the_post(); ?>

is_admin() || add_filter( 'posts_search', function( $search )
{
    empty ( $search ) || add_filter( 'posts_where_paged', function( $where ) {
        return preg_replace(
            '~post_type IN ((.*)'page',?~',
            'post_type IN (1',
            $where
        );
    });

    return $search;
});