Responding to criticism on Sunday, the premier said the gesture only signified his love and care for Paetongtarn, as he considers her part of his family.
Also, he said, his lips did not really touch her hand.
Many Pheu Thai Party critics condemned the action after the clip of the PM kissing her hand went viral.
Several said this gesture showed that despite being the premier, he was kowtowing to the new Pheu Thai leader.
Others likened the gesture to a gangster showing respect to the mafia boss, like in one of “The Godfather” films.
“Does this show that Paetongtarn is a godmother?” one Facebooker asked.
Some critics even went so far as to suggest that the gesture showed that Srettha may step down for Paetongtarn to succeed him as premier soon. Others, meanwhile, asked if Thailand had two prime ministers right now.
Srettha responded to these comments by saying that when Pheu Thai members attend a party meeting, they leave behind their political posts and join as party members.
He said he and Paetongtarn loved and respected each other as family members for a long time.
“It’s just love, attachment and care that we have towards each other. It’s a family affair,” he said, adding that the issue should not be discussed any further.
“It’s the Pheu Thai family and now I’m wearing the hat as the prime minister, while Paetongtarn is doing her duty as the chair of the soft power management committee. We understand each other well and Thailand has only one prime minister.”
Paetongtarn is the youngest daughter of former premier Thaksin Shinawatra, who is considered Pheu Thai’s patriarch.