Toronto reliever Jesse Carlson was also penalized for three games for the same infractions, with both players agreeing to begin serving their suspensions on Wednesday.
Carlson's suspension was originally to mirror a four-game suspension for Posada, but it was reduced to three games for both players -- beginning Wednesday night -- and a smaller, unknown fine, the pitcher told MLB.com.
In all, four members of the Yankees and two members of the Blue Jays were penalized.
Yankees outfielder Shelley Duncan was suspended for three games for his role in a physical altercation with Toronto catcher Rod Barajas near home plate, but Duncan has chosen to file an appeal and his discipline will be held in abeyance.
"I was disappointed with it, but I respect the job the umpires have to do out there and Major League Baseball has to do," Duncan said. "Brawls can turn into really bad things. No one wants them to happen and no one wants to be in them. What everyone tries to do is break them up and get back to playing baseball. I respectfully disagree with the opinion of my role in participation."
Barajas was also fined $1,000 for "verbal abuse," and Yankees hitting coach Kevin Long and pitcher Edwar Ramirez received undisclosed fines for their actions during the incident. Bob Watson, Major League Baseball's vice president of on-field operations, made the announcements.
Posada was not listed in the original Yankees lineup on Wednesday with a stiff neck that manager Joe Girardi said he believed stemmed from the incident.
Girardi said that he wished the events had never taken place, but he would not criticize Posada's actions during the incident, which home-plate umpire Jim Joyce had called "a cheap shot."
"The intensity that we love in Jorgie, sometimes these are the types of things that happen," Girardi said. "I love his heart and I love his intensity. I wouldn't want to take this away from him."
The fracas started to gain steam in the top of the eighth inning in New York's eventual 10-4 loss, when Yankees reliever Mark Melancon hit Aaron Hill in the back with a fastball, the second Toronto hit batsman of the game. Melancon, Posada and Joyce all later declared that pitch unintentional.
"I checked to make sure Aaron Hill was OK, and I feel bad for my guy, Mark Melancon, because I know that he's not trying to hit him," Girardi said. "It's happened a couple of times and I know he feels extremely bad about it. But as I told him, 'This is a learning process and you're growing. You're going to have some tough moments. This has a chance to define how tough of a player you're going to be.'"
Melancon said that he has been fighting a hitch in his delivery that has created a few tense situations. Last month, he buzzed and then hit Boston's Dustin Pedroia, who barked harsh words at the rookie right-hander. Melancon said watching Posada's later actions made his part tough to swallow.
"That was the last thing I wanted," Melancon said. "Obviously, there was no intention there. I'm sitting there thinking, 'Geez, I'm just trying to earn a spot.' The last thing I want is somebody on either side to get hurt. It was unfortunate that it had to escalate to what it did."
In the bottom half of the eighth inning, Carlson threw a pitch behind Posada, which the Yankees backstop took exception to. Benches cleared in that instance, prompting Joyce to warn both teams.
While coming around to score later in the inning on a Brett Gardner double, Posada jabbed an elbow at Carlson after crossing home plate, causing the left-hander to shout at him and both benches to clear once again.
After the incident, Carlson sported a large welt on the left side of his forehead, and Girardi was clipped on the left eye and cut his left ear.
Several media outlets indicated that Toronto's John McDonald had been the person who clipped Girardi, but Girardi made sure on Wednesday to note that those reports were "totally incorrect."
"I got elbowed accidentally by one of my own players that I won't disclose, because it was an accident, trying to pull someone off," Girardi said. "I don't want John McDonald to have a bad name."
Girardi and McDonald met on the field at Yankee Stadium at approximately 3 p.m. ET behind the batting cage to discuss the incident and shook hands before parting ways.
"John McDonald is a local kid that is a good man," Girardi said. "From watching the tape, I didn't see John McDonald touch me. He actually sought me out today and we talked about it. He was quite disturbed that his name was mentioned in that sort of situation. He's a peacemaker."
"I wasn't out there to apologize to him for hitting him," McDonald said. "I just wanted him to know that the only reason I was even on the field was to help break people apart, and he knew that. That's what he was doing. That's what everyone was doing."
Bryan Hoch is a reporter for MLB.com. Jordan Bastian contributed to this report. This story was not subject to the approval of Major League Baseball or its clubs.