The Manchester United defender appeared to kick out at Michy Batshuayi during the first half of Monday's match at Stamford Bridge. The video assistant referee reviewed footage of the incident, and Maguire stayed on the pitch. He went on to score United's second goal in a 2-0 win.
"Maguire should have been sent off," Lampard stated post-match, according to The Guardian's Jonathan Liew. "That's clear, and that obviously changes the game. It's just a wrong decision - everyone I've spoken to has said the same. Which I suppose is harder to take with the presence of VAR.
"Decisions like that are crucial. That's a major part of what VAR was brought in for: a second viewing, different angles. I don't get why they (the on-pitch referees) aren't looking at the monitor. It should be used."
Maguire admitted he "caught" Batshuayi when he faced the media, but he claimed he acted in self-defense and that officials made the correct decision in not showing him a card.
"I felt he was going to fall on me, and my natural reaction was to straighten my leg to stop him," he said. "It wasn't a kick out and I had no intent to hurt him. I apologized to him, and it was nice that the referee saw sense."
United boss Ole Gunnar Solskjaer agreed with his captain's version of events, saying Maguire "was just protecting himself," according to The Athletic's Simon Johnson.
The influence of VAR frustrated Chelsea on two other occasions Sunday. The Blues had an equalizer by Kurt Zouma controversially disallowed due to Cesar Azpilicueta pushing Brandon Williams in the build-up, and Olivier Giroud had a goal chalked off for a tight offside.
Manchester United's victory lifted them into seventh in the Premier League table, three points behind fourth-place Chelsea.