Magennis hit back at raging Rugby Park season-ticket holder Gordon Sawers after the 37-year-old posted a scathing six-minute-long attack on Twitter and Facebook blasting his team.
The expletive-filled video was uploaded following last weekend's 4-0 thrashing by Ross County and has been viewed more than 100,000 times.
During his astonishing tirade at boss Gary Locke and his players, the former Killie youth-team player barked: "It isnae f****** good enough".
He also claimed the squad needed to train harder before berating them for "eating fry-ups and f****** pies instead of bananas and porridge".
But frontman Magennis dismissed the attack from Sawers - who also went on a local radio station to continue his criticism.
Hitting back, the Northern Irishman said: "For me, those kind of people are not fans. If they want to do that, then to me they are poison.
"They pay their money so all due respect. But then they get airtime on the radio and it just gets promoted. For me, people like that are irrelevant to my life.
"If you listen to that kind of stuff and you take it on board, you are not a footballer. For me, that just goes in one ear and out the other."
But Magennis did admit the side had failed to perform this season.
The 4-0 drubbing by the Staggies came just three weeks after Dundee also put four goals past Jamie MacDonald on the opening day of the Ladbrokes Premiership season.
And Magennis, whose side will hope to pick up their first league win when they face Motherwell at Fir Park on Saturday, said: "The Dundee game at the start of the season was an embarrassment to football. It was a disaster. No-one showed up, not even the subs.
"But even though we got beat by the same score at the weekend by Ross County, it was more of a mixed bag. We just got beat by a better team.
"I don't think any of us failed to show up. We just got beat by a better team. We created a few chances but still looked vulnerable in defence.
"It was better but still the same result. A loss is still a loss whether you concede one goal or four."
Killie have managed a credible 2-2 draw with champions Celtic and responded to last week's disaster at home to Jim McIntyre's Dingwall men by beating Berwick 4-1 in the League Cup.
And former Aberdeen and St Mirren forward Magennis has promised the club's frustrated faithful that performances will turn round.
He said: "Has the flak been hard to take? Maybe for some but as a footballer you've just got to take it.
"You are paid to be a footballer and you are in the limelight whether you like it or not, whether you try to go under the radar or not.
"You are always going to get some press. I try not to pay too much attention to the good press or the bad. I try not to get carried away.
"The criticism we have been getting is well deserved because compared to the start we had last season, this one isn't good enough.
"But with the quality we have in the team, of course we believe we can turn it around. I will back us against anyone. Unfortunately so far we haven't hit out stride.
"I'd just ask the fans to stick with us. They have every right to be a bit weary. They pay their hard-earned money to come watch us. We're not entertaining them right now but hopefully we will be playing exciting and expansive football soon. They just need to be patient."