The young Magpies, who flew out to Spain on Tuesday for a six-day training camp in Pinatar, broke the deadlock through Michael Ndiweni's composed finish before the La Liga outfit drew level through Enzo Roco's header.
Elliott Dickman's side regained their one-goal cushion in the closing stages following White's impressive finish from the edge of the box before United's second-string held firm to secure the victory against the Spanish top-flight side, who held Champions League winners Real Madrid to a 2-2 draw at the Santiago Bernabéu in January.
White, who signed a signed a new three-year contract with the Magpies in March, told nufc.co.uk: "I thought we had more of the ball in the first-half than the second but I thought we dug in in the second. Ultimately, the two goals came from counter-attacks and it was good to see it out at the end against senior opposition.
"I've had a taste of men's football from January (playing on loan for Hartlepool United) and it's much more different to under-21s and youth football. It was difficult in the heat, especially when I came on in the first-half.
"The sun went down around the 60th minute which made it much easier, especially in the circumstances when we had to dig in. This week, we've slowly got used to it more and more, which has definitely helped us get the win."
White recorded a total of 13 assists last term whilst featuring for United's youngsters along with a loan spell at Hartlepool for the remainder of the 2021/22 campaign, registering an assist on his professional league debut against Barrow.
After netting the winning goal against Elche, the Cumbrian playmaker - who joined United's Academy in 2016 - is determined to take his goalscoring touch into the 2022/23 season in order to elevate his game to new heights.
"That was something I definitely need to work on and something I want to add to my game," the former England under-18 international added. "There was more than enough assists at the start of last season with Newcastle and even with Hartlepool. This season's aim is to get more goals and keep the assist tally up.
"It gives everyone a taste in playing men's football and not many of those in the squad have had it. Games like this and those in the Papa John's Trophy are the ones everyone looks forward to in playing against men. That's everyone's aim - to play men's football and make a career in the game."
Reflecting on his goal, the teenage midfielder added: "I'd seen the chance to pounce on the centre-back who Michael (Ndiweni) was pressing. I had a chance, took it and saw him looking awkward on the ball so read the pass he tried to play.
"It was a 50/50 between me and the centre-back in order to get it but as soon as I got into that finishing situation, I knew what I was doing, hitting it on my left foot and shooting.
"As soon as I cut in, I'd seen the 'keeper in the corner of my eye and saw he was reading me to whip it into the far corner. I've disguised it and I was pleased with the finish."
