There were 66 pissed off viewers who felt compelled to fire off some emails to the feds about what they saw ... with most up in arms about the violent attack and voicing concern about what their kids saw and heard on TV.

TMZ obtained the complaints made to the Federal Communications Commission -- a U.S. government agency which regulates television -- regarding The Oscars broadcast ... and all 66 were focused on Will slapping Chris and shouting obscenities after the comedian made a wisecrack about Jada Pinkett Smith.

"The level of violence from one black man inflicted onto another over something he didn't like hearing is intolerable!! Are you tolerating this??? Thought black lives mattered?? Obviously not!! Is that your message???? Smith should be fined & suspended!!!!" ... a viewer from Michigan wrote.

Lots of parents complained about their kids witnessing an assault on live TV, claiming it led to some very uncomfortable conversations with their children, including one viewer in Oklahoma who says their kids asked them "if Black men are always violent?"

The slap even brought up memories of the Justin Timberlake and Janet Jackson wardrobe malfunction at the Super Bowl ... with a viewer from Texas writing, "Obviously, the Oscar's crossed a line last night. I should not have to worry about what my CHILDREN are going to hear during the Oscar's presentation. Not delaying the broadcast for whatever reason was a FAILURE on your part. There needs to be fines and people need to be fired over this. Have we not learned anything in the decades since the Super Bowl debacle? Overall, you have a simple job. Do it!"