The 40-year-old also said he is planning on fighting again in 2020, possibly against the winner of the 28 September fight between Errol Spence Jr and Shawn Porter.
In 2017, Khan and Pacquiao were slated to have a bout but an agreement could not be reached between the two.
The Filipino southpaw, who has enjoyed a glittering, 23-year pro career, retired briefly in 2016 but made a comeback to retake his WBO title from Jessie Vargas just months later.
The 38-year-old had said to be considering a second retirement after his loss to Jeff Horn.
Horn welcomed the review when it was announced, and said he was ready for a rematch.
The result of the fight has been widely questioned, with many believing Pacquiao should have won.
Immediately after the fight, Pacquiao had said he wanted a rematch with Jeff Horn.
Pacquiao's trainer advised Pacquiao to quit boxing after his sensational defeat to Horn.
The three judges scored the fight 117-111, 115-113 and 115-113 to Horn.
Pacquiao lost his WBO welterweight world title to Jeff Horn in a stunning, unanimous points decision.
