“My seven year old son is trying to masturbate?”

Normal behavior unless it becomes excessive, obsessive or inappropriate in any way.

Try to distract him. Genitals do produce pleasure & at that age means nothing.

That is normal behavior. Educate instead of chastise.

See this link...
https://www.askdrsears.com/topics/parenting/child-rearing-and-development/sexuality/masturbation-six-ways-manage-it/
and
https://defendinnocence.org/child-sexual-abuse-risk-reduction/sexual-development-at-all-ages/developmental-stages/typical-child-behavior-ages-6-9/
and
https://www.focusonthefamily.com/parenting/what-to-do-when-young-kids-masturbate/

This is very unfortunate situation. More than GP, what you need is to consult with a child psychotherapist, as, unfortunately, one of the reasons for precocious puberty is child abuse or exposure of child to those abusive situations. You will still need to consult with GP to rule out any other medical causes though.

Laeeq Tahir, MBBS., MD., FRCPC

Children learn to masturbate in infancy, we are born sexual, skin and touch being primary sensori-sensual aspects of ourselves (the brain is our second largest "sex organ," the skin being the first). It may be likely he is trying self soothing strategies, and boredom could also be a trigger for your child. This activity is not necessarily an indication of pathology or a reaction to anything he may have seen or witnessed. You can respectfully and gently redirect your child, avoiding panic or shame, into alternative self-soothing or mentally stimulating activities. Working with sand or play-doh, helping with chores, and eventually talking with your child about their body in healthy, non-reactive ways. There are plenty of good children's books on this subject matter to help guide you.