Protection from white means the creature cannot be the target of white spells or abilities from white sources — regardless of who controls those spells or the creature. The protection ability does not distinguish between friendly and enemy sources. This is defined in CR 702.16b, which lists the four effects of protection using the acronym DEBT: the permanent can't be Damaged, Enchanted/Equipped/Fortified, Blocked, or Targeted by anything with the specified quality.
CR 702.16b specifically states that a permanent or player with protection can't be targeted by spells or abilities with the specified quality. There is no exception carved out for spells controlled by the same player who controls the protected permanent. The rule is absolute in this regard.
If you attempt to target your own creature that has protection from white with a white spell (for example, trying to enchant it with a white Aura or buff it with a white instant), the targeting is illegal. If somehow the targeting occurs and protection is gained in response, the spell will be countered by the game rules on resolution per CR 608.2b because its target is now illegal.
Concrete example: You control a creature with protection from white. You try to cast Giant Growth — but wait, that's green. Instead imagine a white pump spell like Guided Strike targeting your own creature with protection from white. You cannot legally choose that creature as a target when you cast the spell; the game will not allow it, even though you control both the spell and the creature.
So the answer is a firm No: protection from white stops all white spells from targeting the creature, yours included.
Unofficial fan resource — not affiliated with or endorsed by Wizards of the Coast. Answers are AI-generated estimates grounded in the Comprehensive Rules and are not a substitute for an official judge. Verify anything match-critical.