I had the same problem and I came up with this solution, hope it helps.
<?php
$terms = get_the_terms( $post->ID, 'product_cat' );
foreach ( $terms as $term ){
$category_name = $term->name;
$category_thumbnail = get_woocommerce_term_meta($term->term_id, 'thumbnail_id', true);
$image = wp_get_attachment_url($category_thumbnail);
echo '<img src="'.$image.'">';
}
?>