Which Hook can I use when creating unique post but not update/save/delete

The save_post hook has a third parameter named $update, so you can use it to check if the post is being created and not updated.

function define_asset( $post_id, $post, $update ) {
    if ( $update ) {
        return;
    }

    // else, run your code...
}
add_action( 'save_post', 'define_asset', 20, 3 );