The Young Lions head coach saw his side held to a 1-1 draw against Holland on Sunday, after leading at the break and creating a host of missed opportunities.
And despite the result leaving England top of Group D on four points going into their final game on Tuesday, Peacock felt his side could have been more deadly in front of goal.
Netherlands 1-1 England
UEFA European U17s Championship
Group D
Sunday 10 May 2015
Beroe, Stara Zagara, Bulgaria
"It was the old scenario of a game of two halves," Peacock told TheFA.com after the final whistle.
"We came out with a slightly different system that the Dutch struggled to deal with. They chopped and changed a little bit in the first half and eventually went to a back three.
"But we needed a more clinical approach to the first period. We probably deserved to be two or three up with a bit better decision making and finishing."
Peacock, who was taking charge of his 100th UEFA game, continued: "I told them at half time it was going to be tough at only 1-0 and with them having nothing lose.
"They probably had the better of the second half - I couldn't see the penalty from where I was but I think the reaction of the players said it all that they didn't think it was a penalty.
"But that's the rub of the green - we should have had one against Italy and then concede one today. But take nothing away from Holland, the quality of play from both sides was top quality and of a high order."
The Young Lions go into Wednesday's final group clash with Republic of Ireland knowing that a point will guarantee their spot in the knock-out stages.
But the two-time Euro winning boss insists his men will be giving everything to get the win.
"This was probably the toughest group of the four and to be sitting on top at this stage is very positive," he added.
"We've gone into every game with a positive frame of mind and we will do so again versus Ireland."
