Following the bout Williams, who fights South African heavyweight Francois Botha next week, tweeted an image with Mundine, claiming victory.
"Hanging out with @Anthony_Mundine celebrating a victory.. We don't pay attention to corrupt judges!!"
NRL commentator Andrew Voss replied: "Careful boys. I think you need to learn about the laws of defamation."
This morning Williams retracted the comment.
"Sorry about the tweet last night. Emotions were running high just very disappointed for my brother and that's how I saw the fight," the former All Black posted on Twitter.
"No disrespect meant to Geale he's a great champion-fighter and it was a great night."
It was Geale's fourth successful title defence and sets up the possibility of more unification bouts down the track.
Mundine was competitive but lacked the explosive advantage in speed that enabled him to beat opponents in his prime and it remains to be seen whether he can, or wants, to stay in a game he has graced for close to 13 years.
The packed crowd provided a stirring vocal backdrop as the two highly skilled fighters each strove to gain an advantage.
Geale was the first to land some shots, though Mundine did briefly back him up against the ropes and caught the champion with a good right to the head in the closing seconds of a cagey opening round.
Both men looked to assert themselves through the jab, but neither landed many scoring power punches in the second round.
American Robert Byrd, who was officiating in his 115th world title bout, twice cautioned Mundine for use of his head during the third round, in which Geale did well early and the challenger lifted near the end.
The fourth featured some exciting inside exchanges with both men scoring, though Geale had a slight edge in work rate.
Geale probably shaded the fifth and sixth rounds with greater punch volume, but Mundine still caught the champion occasionally with a right hand, without landing follow-up blows.
In round seven, Byrd warned Geale for punching to the back of the head.
Mundine got his supporters chanting his name with a good flurry in the eighth, which drew only a smile from the champion.
Geale started the ninth in strong fashion, but Mundine came on strong in the last minute.
The champion pressed the pace in the tenth and maintained his edge through to the end.
The two combatants for the main event didn't step into the ring until after 11.10pm (AEDT), following a six-fight undercard, which produced just one inside the distance result.
The suggestion Mundine would snub the national anthem was averted, as it was performed before both men entered the ring.
As per usual for a big boxing bout, there was a stellar cast of sporting stars, administrators and politicians in attendance.
Geale felt he produced the convincing performance he wanted but could have done even better.
"I would have liked to do it that little bit extra,'' Geale said.
"A lot of people asked me to finish the job and a couple of moments there I had him in some real trouble, I just couldn't find that last little bit.
"He's a great defensive fighter, you can't take anything away from him.''
Geale said he wasn't surprised Mundine had reportedly said he was robbed of the decision.
"It's what you'd expect,'' Geale said.
The Tasmanian-born Sydney-based boxer said he wanted to become the number one middleweight in the world.
His American promoter Gary Shaw said Geale would have options to fight next in either Australia or the United States.
"Personally, I'd love to see Daniel back in Australia,'' Shaw said.
Geale said when he needed to dig a bit deeper he was motivated by some of the taunts Mundine made in the lead-up to the fight.
He said Mundine still had good speed and skill, but just seemed to lack something.
- nzherald.co.nz/AAP
