The Argentina international took a swipe at club chairman Daniel Levy and others in the hierarchy following the enthralling derby loss, where Spurs led 2-0 inside 11 minutes before capitulating after Romero went off injured.
The 26-year-old highlighted the spending power of Liverpool, Chelsea and Manchester City while lamenting Spurs' lack of progress, as the Lilywhites continue to search for their first piece of silverware since the 2007-08 EFL Cup.
Ahead of Thursday's Europa League showdown with Rangers, Postecoglou was inevitably quizzed on Romero's comments, and the Tottenham boss revealed to reporters that the South American had expressed remorse behind closed doors.
"I've already spoken to Cristian about it and and he's apologised for the fact that the way he said it, particularly in the public sense, wasn't the right way to go about things," football.london quotes Postecoglou as saying.
'Romero did not express himself the right way'
"He's a human being, he got emotional and I think he just expressed what he wanted to express, probably in the wrong way. He does care. I think it would have been easy for him not to say anything. He does care, but there's a way to do these things and a way to express yourself and the way he did it wasn't the right way."
As Romero has apologised for his post-Chelsea outburst, Postecoglou does not see the sense in giving him a proper punishment, adding: "I just think you deal with these things internally. I just don't think there's any benefit for us [to punish him].
"I know people get really salacious about punishments and stuff. They really love that sort of thing. I think I'm pretty consistent in saying I don't just think that's important. I think what's more important is an understanding of how we should deal with these things and deal with them better."
Romero made his first start since recovering from a toe injury in the visit of Chelsea, but the centre-back lasted just 15 minutes before being withdrawn with a new muscular problem, one that will allegedly keep him sidelined for as long as six weeks.
The Argentine would likely miss next month's North London derby with Arsenal if such a timeline is accurate, and he was one of three players forced off in the visit of the Blues alongside Micky van de Ven (tightness) and Brennan Johnson (illness).
Will Romero, Van de Ven be available for Rangers clash?
Johnson is likely to be fine for the Rangers showdown, but Postecoglou has confirmed that both Van de Ven and Romero will miss out, adding: "We're still getting some clarity around their prognosis, but both have picked up injuries that will keep them out again.
"That's disappointing for us because we're thin on numbers but we've had to deal with that for quite a while now. Everyone else from the weekend got through OK."
Ben Davies, Richarlison, Guglielmo Vicario, Mikey Moore and Wilson Odobert are also out of contention for Tottenham, meaning that Archie Gray will likely have to fill in as a makeshift centre-back alongside Radu Dragusin, but Rodrigo Bentancur is available for the Europa League fixture amid his domestic suspension.
Spurs and Rangers have both taken 10 points from their opening five Europa League matches this season, but Postecoglou's men are sitting just outside the automatic last-16 qualification spots in ninth place in the table on account of an inferior goal difference.
The two clubs have only ever met twice before in the 1962-63 European Cup Winners' Cup first round, where Tottenham won both legs, although Postecoglou faced Rangers 11 times while in charge of Celtic, masterminding six victories and only suffering three Old Firm defeats.
Written by
Ben Knapton