Dean, who was the VAR for the controversial game at Stamford Bridge, decided against any punishment for Romero at the time.
Video Assistant Referee, Mike Dean has apologized after admitting wrong in the match between Chelsea and Tottenham that ended 2-2.
Dean admitted he was wrong for not telling referee, Anthony Taylor to go to the pitchside monitor to review Cristian Romero’s hair pull on Marc Cucurella which could have led to a red card in Tottenham’s 2-2 draw at Chelsea.
Dean, who was the VAR for the controversial game at Stamford Bridge, decided against any punishment for Romero at the time.
Spurs defender Romero grabbed Chelsea wing-back Cucurella near the end of Sunday's 2-2 draw at Stamford Bridge as Spurs striker Harry Kane nodded in from the resulting corner.
In his Daily Mail column, Dean admitted: "No referee wants to be driving home from a game knowing they should have made a different call. Sometimes in hindsight, you realise you could have acted differently.
"For the second goal by Harry Kane, I asked referee Anthony Taylor to wait while I looked at the incident involving Tottenham's Cristian Romero and Chelsea's Marc Cucurella.
"I could not award a free-kick as VAR, but I could recommend to Taylor that he visit the referee review area to consider a possible red card. In the few seconds I had to study Romero pulling Cucurella's hair, I didn't deem it a violent act.
"I've since studied the footage, spoken to other referees and, upon reflection, I should have asked Taylor to visit his pitch-side monitor to take a look for himself. The referee on field always has the final say.
"It goes to show that no matter how experienced you are, and I've spent more than two decades as a Premier League official, you are always learning.
"It's disappointing for me as this was one incident in an otherwise very good weekend from our officials."
Tottenham's first equaliser was also controversial with Chelsea claiming Pierre-Emile Hojbjerg's goal should have been disallowed for offside with Richarlison in goalkeeper Edouard Mendy's line of sight.
Blues boss Thomas Tuchel was also enraged that a foul was not given for a tackle by Rodrigo Bentancur on Kai Havertz in the build-up to the equaliser.
But Dean believes he was correct to allow the Danish midfielder's goal to stand.
He said: "With the first equaliser for Tottenham by Pierre-Emile Hojbjerg. This one was relatively straightforward. I can't go back 44 seconds to look at Rodrigo Bentancur's potential foul on Kai Havertz. It is outside the attacking phase of play - the Tottenham player got a toe to the ball anyway - so that wasn't a factor in whether Hojbjerg's goal should stand.
"The question was whether Richarlison was interfering from an offside position. When Hojbjerg's shot was struck, Chelsea goalkeeper Edouard Mendy had a view of the ball for me. His line of vision wasn't clearly blocked, so it was onside and 1-1."
Dean will not be in charge of VAR for the next round of Premier League fixtures after being given the weekend off following the controversial events at Chelsea.
The 54-year-old retired from on-field refereeing at the end of last season but has remained involved with the Premier League as a VAR.