Jamal Adams better sleep with one eye open ... 'cause Rob Gronkowski is vowing REVENGE on the Jets safety for his brutal attack on the Patriots' mascot!!!
ICYMI ... J.A. was playing around at Pro Bowl practices last week -- when he went after Pat Patriot and tackled the poor guy to the ground.
Turns out ... Adams really hurt the dude -- NFL Network's Ian Rapoport says the person in the costume is still "dealing with jaw, neck, and back soreness.