Parker, who Milwaukee selected with the second overall pick in the 2014 NBA draft, told ESPN's Eric Woodyard he returns to the city for Wednesday night's game disappointed he's not part of the franchise's resurgence over the past couple years.
"Never. I would never rule out a possible return here," he said. "I would never do that. It's just so sad how it ended and I wish I could've stayed."
The Bucks originally extended a qualifying offer to Parker last year, but they later rescinded it to pave the way for him to sign a contract with the Chicago Bulls. The Bulls traded him to the Washington Wizards in February and he joined the Hawks in July.
It's been a whirlwind stretch and while he's emerged as a key contributor in Atlanta, averaging 16.9 points and 6.1 rebounds across 17 appearances, part of the Duke product wishes he was still in Milwaukee.
"It's real special, man, how they were able to build this building," Parker told ESPN. "I haven't played here but just seeing like the growth of the city, I really like the way that it's developing. It's just so sad that I'm not able to share it with them and that they moved on, but that's fine, that's business, but I do have like a little homesickness from being here. I just miss being here."
The Bucks finished with the best record in the NBA last season at 60-22 and advanced to the Eastern Conference Finals before falling to the eventual champion Toronto Raptors in six games.
Giannis Antetokounmpo and Co. are off to another strong start to the 2019-20 campaign with a 14-3 mark, one game behind the Los Angeles Lakers for the league's best record.
Parker can become an unrestricted free agent again next summer thanks to a player option in the two-year, $13 million contract he signed with the Hawks.
Robin Lopez is the only member of the Bucks' frontcourt depth that can hit the open market after the season, so it's unclear whether Milwaukee would have the space to bring back Parker.