Luiz posted news of his problem, confirming that he would not play against the Royals, on the morning of the match on Wednesday.
Reports claim that the Brazil international has been fined but Di Matteo confirmed only that the issue would be addressed within the club.
"This social media thing is all around us now," he told reporters. "We'll deal with it internally."
|THREE IN A ROW?
|10/1||Chelsea are 10/1 to beat Newcastle 3-1 with Paddy Power|
Di Matteo has looked to create a more adventurous team by signing Oscar, Eden Hazard and Marko Marin this summer but acknowledged that the Blues must find the right balance between attack and defence.
"At 2-1 down, we were very offensive and maybe lost our balance a bit, because we were behind," the Italian said.
"The balance was always going to be the key.
"It's all great and everyone wants to see a lot of flair play but, to win games, you need a good balance to it. That's going to be the challenge."