When I play Crescent Strike, does the one damage also make me pay Deflect?

No, you do not have to pay the Deflect cost for the enemy units that receive 1 damage from Crescent Strike.

According to the RiftJudge FAQ #9516:

"Crescent Strike only targets the battlefield and the one enemy unit you choose. The 'other enemy units' at that battlefield are programmatically selected based on their characteristics (location and controller), so they are not targets."

Deflect (as defined in Rule 809.1.c) only imposes a mandatory additional cost on spells and abilities that "choose" (target) the unit. Because the 1 damage dealt to the other units is an area effect determined by the game state rather than a specific choice of targets, those units are not targeted, and Deflect does not trigger for them.

However, if you choose an enemy unit with Deflect as the primary target of the 4 damage, you would be required to pay the Deflect cost for that unit.