Reports have linked Rocha with a season-long loan switch to the KC Stadium.
Tigers boss Brown confirmed he has held talks with Rocha, but has yet to decide on an offer for the Portuguese defender.
"At this stage it's just about talking to players, inviting them in and seeing the whites of their eyes," Brown told the Hull Daily Mail.
"We've had a bit of a conversation with the player about whether or not he would be keen on coming to Hull City.
"I don't think people see a small club when they see Hull City, they've probably got a judgement call on how quickly the club can progress.
"I know what the player is capable of, but it was a progress report on how he would feel about coming here."