No, you should not walk on concrete roof tiles. Concrete roof tiles are very durable against the elements, but they are not designed to be walked on. Walking on concrete roof tiles can be slippery and dangerous and the tiles are almost certain to break if you walk on them.
If you need a close-up view of something on your roof, use a set of binoculars or aerial photography. If you need to clean or inspect your roof tiles, contact a roofing professional.