Thomas Markle Not Watching 'Harry & Meghan,' Focusing on Health

Thomas Markle is steering clear of his daughter's docuseries, "Harry & Meghan" ... according to Meghan's half sister, who says their father's more focused on his health than the project she calls "disrespectful."

Samantha Markle tells TMZ ... she's protecting her dad by telling him not to watch the new doc, saying Meghan's kicked Thomas while he was down in the past, and a series like this just further disrespects their fam.

Samantha says Thomas doesn't know what's in the series, and doesn't need to find out.

She doesn't think he'd even want to watch, because the royal family ordeal has been damaging to his health for a while. Most importantly, he's still recovering from the stroke he suffered earlier this year.

If you haven't seen it, the Netflix series is essentially the Duke and Duchess' side of everything they've been through -- from their first date to leaving the royal family to dealing with racist British headlines.

It also includes their viewpoint of the drama with Thomas leading up to their wedding, which he famously did not attend. Harry even says how "incredibly sad" it is for his wife to have lost her dad.