And ICC chief executive Malcolm Speed also told Bari that while he would not face disciplinary action on this occasion, the global governing body was determined to close a loophole in its regulations that had seen him escape punishment for his "unacceptable behaviour".
Bari slammed experienced English official Shepherd's performance during Pakistan's 17-run defeat against Australia in the triangular final in Amstelveen, Holland, last Saturday.
He called for the 63-year-old to retire after he judged Pakistan captain Inzamam-ul-Haq caught behind and Yousuf Youhana caught bat-pad, two key decisions in a tight game.
"Shepherd's umpiring decisions were like target killing and cost Pakistan the final. It's time for the inaccurate Shepherd to retire," former wicketkeeper and Pakistan captain Bari said in Karachi on last Sunday.
But in a copy of a "confidential" letter dated September 3 from Speed to Bari, the Australian makes clear the ICC's anger at his comments.
Speed, who labelled Bari's remarks "inflammatory" and told him he was "out of order", referred to clause 2.4 of the ICC's Code of Conduct which makes it an offence to pass 'public criticism or inappropriate comment on a match related incident or match official'.
Punishments for breaking this clause are the equivalent of between 50 percent of the player or official's match fee up to their full match fee and/or a one Test match or two One-day International match-ban.
"You will be aware that a number of players and team officials have been charged under this clause in recent years," Speed wrote.
He added the clause made no specific mention of selectors but stressed: "It is my view that it is strongly arguable that it is sufficiently wide to encompass a selector and, in particular, the chairman of selectors of a member country.
"I understand that the Pakistan Cricket Board (PCB) proposes to charge you under its own code of conduct in relation to the comments that you made about umpire Shepherd.
"Please note that the ICC chief executive has a wide power and a clear duty to lay charges under the Code of Conduct where it is appropriate.
"I have given careful consideration to this matter and have decided in this case to not lay a charge against you.
"I have done this for two reasons. First, as a matter of fairness to you, there is some doubt about whether the definition of team official is wide enough to encompass a selector.
"I will address this immediately and ask the ICC to include selectors as a specific category of officials so that you and other selectors can be in no doubt about where you stand.
"Secondly, I am assured that the PCB has taken appropriate action under its code of conduct to deal with your unacceptable behaviour.
"Wasim, please rest assured that any future public criticism of ICC officials by you while you are chairman of selectors for the PCB will be dealt with very firmly under the ICC Code of Conduct.
"You have been in and around the game long enough to know that you were well and truly out of order in making these comments."
And in a further sign of the ICC's determination to back umpires Shepherd was standing as scheduled at Lord's on Saturday in Pakistan's One-day International against Australia, whereas previously Bari's remarks might have led to his withdrawal.