Ministers have ruled out intervening in the case of a sick baby after a High Court judge ruled doctors could withdraw his life support.
Specialists at Great Ormond Street Hospital said eight-month-old Charlie Gard should be moved to palliative care, against his parents' wishes.
Shadow housing minister Ruth Cadbury called on the Justice Secretary Liz Truss "to do the right thing".
But she was told the "judgement... should be respected".
Charlie has a rare mitochondrial condition that causes progressive muscle weakness and brain damage.
His parents, Connie Yates and Chris Gard, from London, had wanted to take him to the US for a treatment trial.
They said they intended to appeal against the High Court's decision after Mr Justice Francis ruled it was "in Charlie's best interests to let him slip away peacefully".
Speaking during justice questions in the House of Commons earlier, Ms Cadbury asked whether ministers "have it in your heart to look into the case of Charlie Gard".
The MP for Brentford and Isleworth, who represents the baby's parents, said it was a "complex legal case but if the justice secretary has any powers to intervene, I plead with her to do the right thing."
However, justice minister Phillip Lee replied that while the case was "particularly emotive... clinicians at Great Ormond Street have made a judgment in this case and I think that should be respected."
A crowdfunding campaign set up to pay for Charlie's treatment in America has passed its £1.3m target.