Grand Theft Auto V -- Animal Rights Group Demands BOYCOTT

"Grand Theft Auto V" crossed the line by allowing game-playing children to run over, behead and kill animals -- and a prominent animal rights group is calling for a boycott.

Jack Carone from In Defense of Animals tells TMZ ... his group is incensed that Rockstar Games is capitalizing off animal torture -- and it doesn't matter if it's real or fake. He says it perpetuates what he calls "institutionalized violence" against helpless animals.

"The makers of this game have traded decency for money" Jack says, adding, "Encouraging the darkest impulses of young people is not an admirable pursuit."

Regardless ... Carone says, "animals don't need any more targets painted on them in the name of fun."

So we gotta ask ...