The foul was not given by on-field referee Anthony Taylor and Spurs profited as they scored a last-gasp equaliser to earn a point from a 2-2 draw at Stamford Bridge on Sunday.
Chelsea manager Thomas Tuchel criticised Taylor and Dean and Cucurella said it was "very clear" Romero's action was a red card offence.
"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," Dean wrote in a column for The Mail+.
"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."
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