Saneesh Elayadath of News 18 slammed Mangalam and said this was not the way to report a story.
After persuasion attempts failed, the boy’s parents called the police, who broke open the door and took them into custody.
In India, the minimum age for marriage is 21 for boys and 18 for girls.
Six people have been arrested in Kerala, India, after seven children were lured away from an orphanage and sexually assaulted.
The minister said his resignation should not be seen as an acceptance of guilt.
“My resignation is to uphold political morality”, he told reporters.