The two players were involved in a collision at the end of the first half and replays seemed to show the Northern Ireland international spitting at Cisse, who then appeared to do exactly the same.
Referee Anthony Taylor failed to punish either player, seemingly missing the off-the-ball incident.
And, although Van Gaal acknowledges that he did not actually see what happened, he is certain that Evans is not the sort of person who would spit at someone.
"I didn't see it," he began."[But] I don't think Jonny Evans is a spitter.
"Maybe spitting on the floor but we are on the bench and you cannot see from there."
Newcastle head coach John Carver also addressed the situation and, while he too refused to comment specifically on Evans or Cisse, he was not shy in relaying his disgust.
He told the BBC: "You can't do it, can you? It's one of the worst things in football.
"I can't comment on it, I just know there was a fracas on the halfway line."
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