The Brazilian defender was given his marching orders after a crunching tackle on Sead Kolasinac in the dying stages of the London derby at Stamford Bridge.
Luiz was also cautioned earlier in the match after he caught Laurent Koscielny in the face when attempted an overhead kick.
The sending off means Luiz is set to miss Chelsea’s next three games through suspension – a home League Cup tie with Nottingham Forest and then Premier League fixtures against Stoke (away) and Manchester City (at home).
Conte refused to comment on Luiz’s red card after Chelsea drew 0-0 with Arsenal on Sunday, but instead chose to talk about Alexis Sanchez’s foul on the 30-year-old beforehand which he felt should have resulted in play stopping.
When asked about the 87th-minute red card, Conte said: “You know very well that I don’t like to comment on refereeing decisions. It is in the past. Now the only thing I can tell is it is very imporatnt to see what happened before the David Luiz tackle.”
When then asked whether he meant Sanchez, Conte replied: “For sure, that was a foul. But, I repeat, the referee took this decision. If he stopped the play before, it wouldn’t matter.”
He added on a prospective appeal: “I don’t know, I don’t know what happens.
“But, for sure, we have to wait for the referee’s decision to know how many games he will be suspended for.”