The visitors were fortunate to see Papiss Cisse spurn a glorious chance but Leicester might have led after Marc Albrighton was denied by the upright.
Ultimately, they were undone on the break as Gabriel Obertan fired a 71st-minute winner to seal Newcastle's first victory of the season.
It means Pearson's side have a solitary point from three outings following last month's remarkable 5-3 home win over Manchester United but the manager is confident his players have the character to bounce back.
"If you are not creating or taking your chances, it's important to keep a clean sheet and we have been done on the counter-attack from what was a very promising situation for ourselves," he said.
"It's frustrating, there's no doubt about that, but I know that we will get a positive response from the players."
Kick-off was delayed by an hour at St James' Park due to safety issues surrounding a newly installed big screen.
Pearson insisted the situation had no impact on his players and their final preparations, and stated there was no ill-feeling towards Newcastle over the highly unusual incident.
"The players were all very relaxed about that," he added.
"Both sets of players dealt with the situation very well, as did the club and the officials.
"There was no friction at all. Sometimes these things happen and you have got to deal with them."
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