The pair clashed in 2011 when Gatland publically questioned Hartley's temperament, but the Lions boss has claimed that there is no animosity after selecting the 27-year-old in his 37-man squad.
"I've got a lot of respect and time for Dylan, despite what people might think. I don't want to raise the issue, but I made the comments that I made because of the way in which Dylan was advised to speak about how a player was suspended and that upset me," Gatland told Sky Sports News.
"The reaction didn't really fit for me - a tough front row forward and a Kiwi boy brought up in Rotorua. If someone grabs you by the eye and you don't have a reaction, yet it's so painful afterwards.
"I said the things I did. Afterwards I went up to him, shook his hand and told him I was a little bit over the top in what I said. He respected that. His form has been good recently, but Rory Best was really unlucky."
The tour gets underway on June 1.