This code allows you to add a rel="nofollow" to your WooCommerce products that appear in the loop. [datafeedr]

add-rel-nofollow-to-woocommerce-product-links.php

<?php

/**
 * Remove the woocommerce_template_loop_product_link_open() function from the
 * WooCommerce "woocommerce_before_shop_loop_item" action.
 *
 * @see remove_action()
 */
add_action( 'wp_head', 'mycode_remove_woocommerce_template_loop_product_link_open' );
function mycode_remove_woocommerce_template_loop_product_link_open() {
	remove_action( 'woocommerce_before_shop_loop_item', 'woocommerce_template_loop_product_link_open', 10 );
}

/**
 * Attach our own function to use in place of the woocommerce_template_loop_product_link_open() function to
 * the WooCommerce "woocommerce_before_shop_loop_item" action.
 *
 * @see get_the_permalink()
 */
add_action( 'woocommerce_before_shop_loop_item', 'mycode_template_loop_product_link_open', 20 );
function mycode_template_loop_product_link_open() {
	echo '<a href="' . get_the_permalink() . '" rel="nofollow" class="woocommerce-LoopProduct-link">';
}