Kazee plans to appeal the fine, a source told ESPN.
The league did not take any further discipline against Kazee, who is set to return to the lineup for this week's NFC South showdown with New Orleans.
As Newton slid to the ground, Kazee went low and made contact with his helmet, causing the quarterback to go to the sideline momentarily to be checked by the medical staff.
Smith, who received an unnecessary roughness penalty to offset Kazee's, suggested on Twitter on Friday that Kazee's fine would have been higher had he hit a different quarterback:
I hate to see any player lose money but if that hit was on any other QB but Cam that fine would've been a trillion dollars pic.twitter.com/hPycXhLL4g— Torrey Smith (@TorreySmithWR) September 21, 2018
McKinley also commented on Twitter, writing "'Fine me later' it finally happened," to which Kazee replied, "I'll help you bro." McKinley then wrote back: "Brotherhood I'll do it again if I had to."
Kazee told the media this week: "Just overplaying it; I was playing too fast. Need to learn when to take my shot, when to not take my shot. When he was sliding, I was already in the air; tried to lean over to the left and nipped him with my facemask. Apologize for the hit and everything.''
Newton said on Wednesday he didn't get an apology.
"At the end of the day it's football,'' Newton said. "I don't have no ill will towards [Kazee]. It is what it is. I'm just focused on the Cincinnati Bengals right now and moving on.''
Falcons coach Dan Quinn said the team agreed with the call after reviewing the film.
"We totally supported the call on the field from the officials,'' Quinn said. "But the first guy in the locker room to meet everybody was Kazee. He certainly was disappointed he wasn't able to finish the game with his guys. Shows a lot about the teammate that he is, what he stands for. We're going to work to get that part of his game right. He will, too.''
Kazee was in the starting lineup last week after the Falcons lost starting strong safety Keanu Neal to a season-ending ACL tear. Kazee actually started at free safety, with starting free safety Ricardo Allen moving over to strong safety.
Kazee was flagged for two helmet infractions during the preseason, including one that resulted in Jacksonville wide receiver Marqise Lee being lost for the season with a knee injury. Kazee was not fined for either infraction.