Harry and Meghan sat down with the US chat show host in March.
During the interview, Harry told Oprah that his brother Prince William is “trapped” in the Royal Family.
He said: “My father and my brother, they are trapped.
Royal expert Camilla Tominey said Kate had high hopes of building bridges with the Sussexes before their tell-all interview.
She wrote in the Telegraph: “I have been reliably informed she was even telling her friends before the Oprah interview that she did not think it was too late to ‘pull them back in’.”
Ms Tominey explained how Kate is still keen to “bury the hatchet” with Meghan and Harry even after the Oprah interview.
She wrote: “Having grown up being close to her own siblings, Pippa, 37, and James, 34, the Duchess remained keen to bury the hatchet even after the interview aired to a global audience of millions, seemingly for the sake of two-year-old Archie’s relationship with his cousins.”
A source added: “Her natural instinct is to try to smooth things over.”