The 29-year-old midfielder played 45 minutes of the Selecao's record loss at the World Cup, as the hosts departed the competition at the semi-final stage.
"I'm not sure how long it will take for me to get over this," the Manchester City midfielder is quoted as saying by BT Sport. "This pain is big, big.
"The people wanted a good result, a win, the title, but we lost in the semi-final and all we can do is say sorry."
Brazil will now face the Netherlands on Saturday night in the third-place playoff.