McClaren’s side are second-bottom of the Premier League ahead of Sunday’s home game against Liverpool.
The club’s head coach is the bookmakers’ favourite to be the next managerial casualty in the top flight after dismal back-to-back defeats.
Shearer, the club’s all-time record goalscoring, was damning in his assessment of United’s 3-0 loss to Leicester City on Match of the Day.
And he had a 30-second rant on the programme after last weekend’s 5-1 loss to Crystal Palace.
Shearer said: “It’s very difficult to sum up Newcastle’s plight in 30 seconds, but I’m going to try.
“You cannot coach players who don’t want to be coached, who are not good enough.
“They have got too many Monday to Friday players – good in training, but don’t want to perform on a Saturday
“From the manager’s point of view, I don’t see a plan.
“I didn’t see a plan three weeks ago at Bournemouth, I didn’t see a plan last week against Leicester, and I certainly did not see a plan (against Palace) to stop the opposition.
“Recruitment ... the guys in charge of recruiting players have got away with it for such a long time now at Newcastle because the players they have signed are just not good enough, simple.
“Apart from that – it’s great.”
Asked about Shearer’s critique, McClaren insisted he didn’t “tend” listen to what was said on Match of the Day.
However, McClaren added he “respected” the opinions of those, like former England captain Shearer, who have played the game at the “highest level”.
And he also labelled some of what has been said about the club and his team “interesting”.
“I tend not to listen to pundits on Match of the Day or any other programme,” said McClaren.
“People make me aware (of them), and they’re interesting.
“I’ve been a pundit myself and it’s a great job. It’s the best job in the world!
“Football’s about opinions. There are lots of TV and radio programmes. When you’re asked, you have to give an opinion.
“It’s what you’re paid for. You respect that opinion from people who have played football at the highest, highest level. I’ve got no criticism of that.
“But we tend not to focus (on them), though one or two things are very interesting.”
McClaren again refused to criticise his players at yesterday’s pre-match Press conference.
The 54-year-old repeatedly talked about “confidence” – or a lack of it – in his ranks.
McClaren said: “Nobody is happy at this club.
“We have lost two games and not performed well. It’s a turnaround since Bournemouth (where Newcastle won 1-0).
“Confidence can be eroded as quickly as it comes. The next game is an opportunity to build a performance and get a result.
“Then, confidence comes back. We have done that at times this season.
“We believe in the players. Confidence is fragile, but it is a chance to get a result and a performance and build the confidence.
“When these players are confident, they are good players and a good team.”
Asked if he had enough “character” in his team, he went on: “People question it, and it appears that way.
“But these are young players. They have to come through the adversity at a big club and be stronger when they come out of it.
“We have to claw our way back. That comes from within. Good performances, good results changes it.
“We had a scrape with it (relegation) last season.
“We know where we are, how many games to go. It is not a situation to say we need these points or that game – it is about Sunday.”
McClaren and his players were booed after the Palace and Leicester games.
And McClaren knows fans are losing patience with him.
“It is the same with every football club when you don’t win matches,” he said.
“We work, deal with it and perform.
“I would say never under-estimate the influence the fans have.
“We have won four or five games in a year. That doesn’t build very much belief and confidence.”
Asked if the players still “cared”, he added: “Yes.
“Cross that white line in front of 52,000 and you have to try.”