The pair, both 15, were questioned following complaints that a girl had been targeted in Ballymena, Co Antrim, where sectarian tensions have been on a knife-edge.
The alleged victim, aged 16, was threatened because her parents are of mixed religion, her mother claimed.
Police were told she was confronted by two girls, backed by a crowd of youths carrying Gaelic hurley sticks, as she boarded a bus home from school.
Her mother said: “They were battering on the window saying to her ‘You’re next, you’re dead’.
“She was hysterical and my 13-year-old son who was with her was hysterical.”
The Police Service of Northern Ireland later confirmed two 15-year-old girls had been arrested and interviewed.
“They have been released pending police reports,” a spokesman added.
The alleged victim’s family, who do not want to be named, are Protestants who once lived in the town’s strongly Catholic Dunclug estate.
They moved to Scotland in a bid to escape the twin threat of sectarianism and drugs which has bedevilled Ballymena.
When ill-health forced the mother to return with her four children three years ago, they moved into the loyalist Ballykeel area.
Her daughter, a GCSE student at Dunclug High School, maintained friendships with Catholics and was regularly in the company of Michael.
She was devastated when the 15-year-old Catholic died on Monday after a gang beat him with baseball bats. Five teenagers have been charged with the murder.
“She was distraught after Michael died. I had to stay up with her all that night,” the girl’s mother said.
“Her Catholic grandmother gave her a candle and she brought it round to our home and lit it for that wee boy.
“They used to joke about. She once wore his Celtic top and he had on her Rangers necklace for a laugh.
“She is friendly with both sides of the community and that’s why we think she was singled out – because they know she has a Protestant mum and a Catholic dad.
“She used to get called a ‘Half a Jaffa’ around Dunclug because she’s from a mixed relationship – only Orange in the middle.”
The woman, a retail manager, said her traumatised daughter has been given permission by the school to only come in for GCSE examinations.
“They have assured me they can guarantee her safety when she’s on school premises, but they want her grandfather to escort her in and collect her when each exam finishes,” she said.
“Do people think this is what Michael’s mother would want? Another innocent child receiving death threats?
“My daughter has done nothing and I don’t want to be living in fear.
“But there’s a really horrible atmosphere in Ballymena. With me working in the town centre you can feel it.”
Police said extra patrols have been put on the streets of the town in a bid to prevent further attacks.
“We are paying particular attention to places were young people would congregate,” the spokesman said.