The Metropolitan Police chief said a campaign launched to identify possible victims of female genital mutilation (FGM) "warns" people of the law.
Sir Bernard Hogan-Howe said: "They have an option to stop - the fact they bought a ticket to me is irrelevant.
"They should not be committing a serious attack on a child and they should not be breaking the law."
More top news
Sadiq Khan has weighed in on the debate over the burkini being banned on some French beaches saying women should not be told what to wear.
The USA women's football team goalkeeper Hope Solo has received a six-month suspension for comments made.
The mobile messaging service Whatsapp is going to start sharing users' phone numbers with Facebook, to ensure "better friend suggestions".