In bowl of food processor, combine dates; dried tart cherries; walnuts; oats; cocoa powder; seeds, if desired; salt; and nut butter. Pulse 30-60 seconds until ingredients are ground into tiny pieces.
Add tart cherry juice in 1 tablespoon additions, pulsing mixture after each addition, until crumbly dough forms.
Transfer dough to bowl and fold in chocolate chips.
Roll dough into 12 balls. Serve plain or finish balls with dusting of cocoa powder or drizzle of melted chocolate, if desired.