3:33 PM PT -- Speaking on behalf of himself and his dad, Thomas Markle Jr. tells us, "First of all, Jeff Rayner being threatened by a 78-year-old man who had a heart attack and stroke recently and walks with a cane poses a threat to you -- that's ridiculous and pathetic and embarrassing on your behalf."
He continues, "And on another note, you should file one on me also because I feel the same way as my father feels toward you and your company Coleman-Rayner."
Thomas Markle is out for revenge -- vowing he'd kill a tabloid owner who he feels wronged him -- and now the man wants a court to step in and force protection.
Jeff Rayner -- co-owner of tabloid and news agency Coleman-Rayner -- says he's scared of what Markle might do ... this after Meghan's father allegedly threatened Rayner in a recent book.
According to the restraining order, obtained by TMZ, Markle is quoted as saying, "I got screwed by Rayner and I'm going to find a way to screw him over before I die. I want to tear him down. If they tell me I've got terminal cancer, then I'll kill him because I have nothing to lose."
The book in question is Tom Boyer's "Revenge: Meghan, Harry and the War Between The Windsors."
In the docs, Rayner says, "Since he is 78 years old I anticipate he will use a gun or other weapon" to carry out a possible attack. The tabloid honcho says the thought of Markle getting revenge has caused him anxiety and stress during his daily life.
As for the beef between Rayner and Markle ... Thomas sued Coleman-Rayner last year, claiming an agreement the two parties made for staged photos ruined his relationship with his daughter Meghan and son-in-law Prince Harry.