Creasturs that enter attacking never attacked, and such triggers therefore don't trigger. To attack with a creature means to declare is as attacker in the declare atackers turn based action.

508.4. If a creature is put onto the battlefield attacking, its controller chooses which defending player,
planeswalker a defending player controls, or battle a defending player protects it’s attacking as it
enters the battlefield (unless the effect that put it onto the battlefield specifies what it’s attacking).
Similarly, if an effect states that a creature is attacking, its controller chooses which defending
player, planeswalker a defending player controls, or battle a defending player protects it’s attacking
(unless the effect has already specified). Such creatures are “attacking” but, for the purposes of
trigger events and effects, they never “attacked.”