Guillen was ejected for arguing with home plate umpire Todd Tichenor over a called third strike on Paul Konerko. Shortly after the ejection, Guillen tweeted: "This one is going to cost me a lot of money this is patetic [sic]." A second message soon appeared: "Today a tough guy show up at yankee stadium." He apparently was referring to Tichenor.
According to MLB rules, all social media messages must stop 30 minutes prior to the first pitch, and they can resume after the game at the individual club's discretion. Getting ejected is not an exemption from the rules.
"When I talked to [MLB], I said, 'What do you want me to say?' It's my fault. It's my problem," Guillen said Friday. "Do I regret it? Not in that moment. The only thing I regret is that I'm going to let the team by itself for two days. But [tweeting is] something I shouldn't be doing during the game."
"At first they were a little confused because they thought I was taking advantage of the umpire because he was a kid," Guillen said. "I didn't know who he was. I talked to them about exactly step-by-step what happened and they understand a little bit better my point ... When I take a punishment, I take it like a man."
MLB senior vice president of baseball operations Peter Woodfork confirmed Thursday that Major League Baseball has not had to deal with a player, coach or manager sending out social media messages while a game was still in play, and there was no standard policy on how to discipline the action.
Guillen's case was reviewed by the staff that is headed by new executive vice president of baseball operations Joe Torre.
White Sox general manager Ken Williams said he's not surprised by the decision to suspend Guillen.
"I don't particularly understand the whole social media thing," Williams said. "I understand how it can work for you at times, but I certainly see more of the pitfalls. I don't get it. I don't get why people would want to tell all of their business and their whereabouts all the time, but maybe I'm just old-fashioned."
Williams said he agreed with the league's punishment and said he knew it was a matter of not letting social media usage get out of control around baseball.
"They're absolutely right handling it in the fashion they did," Williams said. "If I'm sitting in Joe Torre's chair, I'd make the same decision that he just made -- and that's with the mindset that it's in the best interest of baseball.
"Now, from the selfish point of view, sitting here as the general manager of the Chicago White Sox, well, I'd like to have my manager managing [Friday night's] game."
It's not the first time Twitter has gotten a member of the Guillen family in trouble with the White Sox. Guillen's son, Oney, left the team's scouting department after some posts criticized the front office in spring training 2010. The episode led to season-long friction between Guillen and Williams that had been patched up.
Guillen has had numerous outbursts during his managerial career, which began in 2004. Among his targets have been Yankees star Alex Rodriguez, umpire Hunter Wendelstedt and former teammate Magglio Ordonez, who currently plays for the Detroit Tigers.
Guillen was ordered to sensitivity training in 2006 after calling former Chicago sports columnist Jay Mariotti a derorgatory name.
He apologized to Rodriguez for comments he made in a Sports Illustrated article in which he criticized the Yankees' star third baseman for waffling on his choice of countries for the World Baseball Classic and suggested he was a hyprocite.
In his first season as manager, Guillen called Wendelstedt a liar. Later in the season, Guillen sarcastically referred to Buck Showalter, then with the Texas Rangers, as the best manager in the history of baseball and the guy who invented the game -- all after Showalter questioned Guillen's knowledge of the rules.
Guillen also went off on a profanity-filled rant against Ordonez, a fellow Venezuelan who left the White Sox and joined the Tigers. Guillen went on yet another tirade after a radio host questioned his lineup on the air.
Guillen said he still plans to tweet, just not during games.
"That's the first time I ever, ever, ever, ever tweet about baseball," Guillen said. "And look what happened. Well, I learned a lesson. Am I still going to tweet? Hell yes. That's my private life."
Information from ESPNChicago.com's Doug Padilla, Bruce Levine, Kevin Allen and The Associated Press contributed to this report.