A enemy wizard cast lightning bolt while within five feet of a tempest domain cleric. The cleric inquired if the lightning bolt triggers the wrath of the storm feature since the enemy wizard was "attacking him."
Wrath of the Storm description says:
When a creature within 5 feet of you that you can see hits you with an attack, you can use your reaction to cause the creature to make a Dexterity saving throw. The creature takes 2d8 lightning or thunder damage