Can I hammer nails in this type of brick?
You will not want to try hammering a nail into that type of brick. The brick material will simply chip away and make a depression and eventually a larger hole. 

I have my doubts that you would have any good result from trying to drill into this type of brick using a masonry bit in an electric drill. The thin walls and many open spaces indicate that there would be poor engagement for most expansion type wall anchors. 

If it was me I would attach a wooden hanger rail horizontally across the wall using a construction adhesive to attach it to the bricks. This could be placed at the height if the pictures or could be installed near the ceiling. You then attach your picture hangers to this wooden rail. In the latter case with the rail near the ceiling you can hang the pictures using two vertical drop down wires from the rail to the picture.