Hebephilia and ephebophilia
Hebephilia is the term used to describe a preferential sexual interest in pubescent (i.e. early adolescent) individuals, rather than adult partners. As with paedophilia, it is not a term that would be applied to under-16s. A related term is ephebophilia, used to describe a preferential sexual interest in adolescent individuals (usually mid-late teens).
Hebephilia and ephebophilia are not formally defined as specific clinical disorders, but if the focus of the sexual preference leads to problematic behaviour and/or emotional distress, and if these problems are persistent (more than 6 months), they would likely meet ICD-10 criteria for disorders of sexual preference. This would need to be assessed by a professional.