Halle Berry's Son Wants To Testify In Parents' Custody Battle

Olivier Martinez says his son with Halle Berry was afraid nobody would believe his abuse allegations against his mother ... so he snapped a photo to back up his story, and now he wants to testify in court.

In new court docs, obtained by TMZ, Olivier claims their 13-year-old son Maceo took a picture of Halle following an alleged physical altercation at her home on September 26, which set off a custody war.

Olivier says Maceo had previously made allegations about his mother getting physical with him but felt nobody took his complaints seriously ... so this time, he says his son wanted photographic evidence.

And that's not all ... Olivier is firing back at Halle's October 5 emergency court filing, calling it "retaliatory" and claiming she is misleading the judge about their son's medical treatment.

He claims Halle painted him as an uncooperative father who was standing in the way of Maceo's care ... even though he says their son's pediatrician and psychiatrist decided September 21 that he should not take medication at this time.

Olivier says Halle knew about the decision and acknowledged it in writing, saying she is now pushing a "false narrative" to the court and public.

Meanwhile, Olivier says Maceo wants to speak directly to the judge about his custody preferences and what allegedly happened at Halle's home. He argues their son deserves to tell his side before the court makes any further decisions.

As TMZ previously reported ... Olivier obtained a temporary restraining order after he claims Maceo told him Halle choked him during an argument over him playing a VR game.

Halle denied the allegation, saying the two were roughhousing ... and she has since completed a court-mandated parenting program amid the bitter custody battle.

The exes are due back in court Friday.