The exclusion of the 29-year-old was unexpected, as the five-time world champions have already qualified for the 2010 World Cup, and their next games are not particularly important.
Dunga implied that AC Milan midfielder Ronaldinho could be called up to Brazil's squad should he hit top form.
"He is a great champion. He has exceptional qualities. We have to help him by not publishing negative stories about him in this moment," the Brazilian coach said.
"I am not asking you to stop criticizing Ronaldinho, but you cannot invent stories."
Spanish paper Sport has recently reported that the talented playmaker was considering retirement, but the former Barcelona star strenuously denied the claim later on.
"We need to show him some respect and leave him be until he returns to being the player that everyone knows he can be," Dunga added.