The former skipper also said that he does not think that Maxwell deserved to be axed from the 14-man squad against England for the upcoming Gillette ODI Series.
"I found it all a bit strange. There must have been a reason why Steve Smith said that but I'm not sure it needs to be a public comment," Waugh told, according to cricket.com.au.
"Just looking at the way he trains, I think he could train a little bit smarter," Smith had said in a press conference in Sydney.
The captain had further said that Maxwell should ditch the "funky stuff" and stick to the basics if he wants to get back in the national one-day team.
"We've all seen the way he can come out and play and do all his funky stuff and be pretty cool with that, but when he puts his head down he's actually a really good batsman," Smith concluded.
However, Waugh strongly believes that such feedback should remain private as it could have a negative impact on the relationship between the two players.
"As soon as you make a statement like that it does put a split between you and the player and it's a pretty personal sort of comment that he's not training hard which suggests he's not professional," Waugh added.
Maxwell's exclusion did raise some questions as the 29-year-old has been in career-best form in domestic cricket and the Big Bash League (BBL).
The all-rounder entered the BBL break of the JLT Sheffield Shield as the competition's highest run-scorer with 590 runs at 73.35, including a staggering 278 against NSW Blues at North Sydney Oval.
However, Maxwell's ODI form has been inconsistent in the last one year.
"No-one is in any doubt about Glenn's ability or his potential to produce match-winning contributions with the bat," national selector Trevor Hohns had said in a statement.
"What we have wanted from him is more consistency but in his past 20 matches in this format he has averaged 22 and we need more than that from a player in the side's batting engine room," Hohns added.
Hohns also said that the selection panel has picked this squad with the 2019 World Cup in mind as Australia aim to defend the title they won three years ago. (ANI)