'Dance Moms' Stars -- BLOCKED from Tweeting at Co-Star ... Following Alleged Attack

"Dance Moms" star Kelly Hyland has been legally FORBIDDEN from having any contact with co-star Abby Lee Miller after a nasty catfight ... which means they can't even tweet each other, TMZ has learned.

Hyland was in court this morning in NYC facing assault and harassment charges after allegedly attacking Miller -- who owns and runs the dance studio -- in a fit of jealousy back in November.

As we previously reported, sources tell us the two women had a hair-pulling brawl at the dance studio after Kelly accused Abby of slighting her young daughters.

Both women showed up at the courthouse this morning ... and so did a camera from Lifetime ... 'cause you KNOW this is going to be part of the TV show.

During the hearing, Hyland was ordered by the judge to stay away from Miller while the case is pending ... which means no talking, no phone calls and NO TWEETING at her.

#drama.

12:30 P.M. PT -- Outside court, Miller vented for the cameras ... accusing Hyland of playing a dumb blonde to get attention.