Clough said he was disappointed his side did not heed his warning of avoiding going behind at all costs against a Sutton side so hard to break down.
It was an end to the club's record 11-game league winning streak at home and saw rivals Port Vale open a six-point gap to third place, albeit it a game in hand for Clough's men.
“We have to respond on Monday,” he said.
“We were looking for four points over Easter, six if we could. It makes it a very big game at Carlisle.
“First and foremost we must not give schoolboy goals away like we did on Saturday.
“We have to move on.”
On the Sutton defeat, he said: “What we said all week was do not go 1-0 down against this team, so to go 1-0 down in the circumstances we did set the game off and was a result-defining moment. And to give them a two-goal lead made it incredibly difficult.
“The early goal gave them a massive lift and confidence and, more importantly, it gave them something to hang onto which they did very well as they're that sort of team.
“They scored early when we played them away and we struggled to break them down.”
He added: “To win 11 on the trot here and not make it 12 in the manner that we did is the worst part.
“We know we will lose games, but to lose it in that manner, was the most disappointing, contributing to it ourselves.
“The timings of the goals conceded was very poor.
“Just when you wanted to get a foothold in the game and and try to build some momentum second half, within two or three minutes we were 2-0 down and they are cock-a-hoop, It's very difficult to come back from there.
“Just when we get one back and you think we can have a go at them we go and give another goal away.
“We were not good enough today on or off the ball. We looked a bit disjointed and injuries are catching up. We missed Stephen McLaughlin's driving force at left back.
“You get days like this throughout the season but we've not had one for a few months with uncharacteristic mistakes.”
Clough has several players out injured he has to consider whether or not to risk at Carlisle.
“We are very conscious if these injuries go, they are missing for a month to six weeks,” he said.
“So, even though there are only five games left, we still have to be careful with them.
“Rhys Oates will be back on the grass to do some training this week but Monday will probably be too soon.
“Sometimes you can get away with it but other times, like today, it shows up when you're missing these type of players.”