Smith struck out angrily at team-mate Williamson after Newcastle conceded a late goal, but manager Chris Hughton claimed he was pleased at the flare-up.
Hughton said the altercation, which forced Kevin Nolan to separate the two, showed their passion.
Newcastle became infamous in 2005 when Lee Bowyer and Kieron Dyer fought each other, so Hughton should be grateful Nolan prevented the latest on-pitch dispute from escalating.
"They're not always like that," said Hughton of the rowing pair. "You don't like these moments. They have to be done in the right way and for the right reason. The reason was that we were disappointed to concede a goal.
"What it shows is that we've got a group of lads with a real desire not to concede goals. If you go into the changing room a minute after the game, everyone's hugging each other."
Nolan added: "Willo headed the ball down and it went right to one of their players and no-one was around him. Alan had a pop but he didn't realise we were marking the other seven behind him. It was handbags and we just got on with it."