Rangers manager Chris Woodward also received a one-game suspension "as a result of Gibaut's actions," MLB said in a statement Tuesday.
Woodward served his suspension Tuesday when the Rangers faced the Padres. Gibaut has elected to appeal and was active for the game. They were both fined an undisclosed amount.
Tatis missed a take sign and swung on a 3-0 pitch with the bases loaded and the Padres sporting a seven-run lead in the eighth inning. Woodward immediately displayed his displeasure with what he perceived as a violation of an unwritten rule of baseball. After the game, the skipper said the pitch got away from Gibaut.
"I'm not pounding my fist on the table saying this was absolutely horrendous," Woodward said of Tatis' swing before the suspension was announced. "I just thought it went just past the line."
Padres manager Jayce Tingler said after the game that Tatis missed the take sign from third-base coach Glenn Hoffman. Tatis said after the game he wasn't aware of such a practice and promised to learn from the experience.
"I've been in this game since I was a kid," he said. "I know a lot of unwritten rules. I was kind of lost on this. Those experiences, you have to learn. Probably next time, I'll take a pitch."
Before Tuesday's game, Tingler said he won't put restraints on the 21-year-old who began the day leading the majors with 11 home runs and 28 RBIs. He also said he was glad Tatis missed the sign.
"We were certainly looking to score more runs and put that game away," said Tingler, adding that his club, which is seeking its first winning season since 2010, has struggled to do that. "We're not looking to break any unwritten rules. We're looking to win the game."
Tatis' decision to swing became a hot topic on Tuesday, with former and current players and managers across the sport weighing in on baseball's "unwritten rules."
"I think it's a little bit silly. I think the needle has moved a long way in that regard," Yankees manager Aaron Boone said before a game against Tampa Bay.
"And not to straddle the fence too much, but I do think there's a sportsmanship etiquette element to things. But I think, look, now more than when these started even 10 and 50 and 100 years ago, things are different," he said.
Boone's father and grandfather both played in the majors. Tatis' dad also was a big leaguer.
"You guys have heard me talk about the run rule from time to time, in the regular season, and then it takes away all unwritten rules," he said. "But I do think the needle's moving closer in a direction where if you really break it down, guys aren't and should not be offended by, for example, somebody swinging at a 3-0 count last night."
"I would just say this is a long conversation that we should sit down and have a glass of wine over and really talk cause I do believe there is some nuance to it," he said. "So I'm not all the way in the camp of just throw it all out and do whatever you want, but I do think a lot of it is outdated and really silly when you really think about it."
Information from The Associated Press was used in this report.