Thomas Markle has asked Prince Harry to "man up" and meet him, as he spoke about how much he misses his daughter Meghan.
The father of the Duchess of Sussex, who has said he is willing to testify against Meghan as part of her legal action against three newspapers, said people should think about what it feels like to have a family member "ghost" them before judging him.
Mr Markle described the breakdown of his relationship with his daughter as "ridiculous", and called for a reunion.
In an interview on ITV's Good Morning Britain, he said he is "really disappointed" he has not seen his grandson Archie Mountbatten-Windsor, adding: "And I really miss my daughter."
He said his message to Harry is: "Man up and fly down to see me. And we'll talk."
Asked what he would say to Meghan, he told the programme: "I'd say 'I love you' and 'let's sit down and work this out.' She was the closest thing to me for years and years and years, until she went off to college and even then.
"This is ridiculous. We should get together."
Mr Markle is the main witness for Associated Newspapers, owner of the Mail on Sunday and MailOnline, in its response to Meghan's legal action over an article featuring parts of a handwritten letter to her father.
The duchess's defence team is seeking damages from the publisher for alleged misuse of private information, copyright infringement and breach of the Data Protection Act.
In court documents, the publisher argues an article in US People was sanctioned by the duchess and its effect "was to suggest that Mr Markle has made false claims about his dealings with his daughter and that he was entirely at fault in not attending the royal wedding and for the estrangement between himself and the claimant".
"I'll see Meghan in court," Mr Markle said to The Sun.
"I wish it hadn't come to this, but I will certainly testify against the things that have been said about me.
"When me and Meghan end up in a courtroom together, it will be quite stunning for everybody."
Asked about the possibility of meeting Meghan and Harry at court as part of the legal action, Mr Markle told Good Morning Britain: "If it comes to meeting them in a courtroom, that's great. At least I'd finally get to see them."
He went on to say he did not want a "battle".
Legal documents submitted to the High Court shed light on the relationship between Meghan and her father, with Mr Markle claiming he contributed tens of thousands to her education, paying private school fees, university tuition costs and her student loan even after her career as an actress took off.
Asked about how he is trying to contact his daughter, he said: "For me, there is no other way to reach them. I pretty much will give an interview and wait for 30 days for some kind of answer back.
"If I don't get one back then I'll try another interview."
Asked what he would say to people who are critical of him doing TV interviews, Mr Markle said: "I would tell them to try being in my position for a while and see what it's like - have a family member ghost you and not speak to you, and see how you feel.
"It's something that stays with you 24/7 every day, and it never goes away.
"It's always on your mind. You wake up with it. You go to sleep with it. It's very hard to deal with."
Harry and Meghan are dropping their HRH styles and stepping down from royal duties in search of freedom away from the monarchy, and will raise Archie mostly in Canada.
