The Mexican had failed to make the top 10 in qualifying, knocked out in Q2 with a lap time 0.015s slower than Daniel Ricciardo's on his RB.
Perez started the race on hard tyres in a bid to make the most of any timely safety car intervention, virtual or otherwise, which failed to materialise as the whole race was run uninterrupted.
Perez did manage to outperform both RB cars and Nico Hulkenberg's Haas, but he finished only eighth, 55 seconds adrift of team-mate Verstappen, in what he called "just a very tough race".
"We sort of knew that was the best we could get. We obviously knew the hard was going to be difficult initially, but we were hoping for a safety car at the right point, that potentially could put us back in the fight," the Red Bull driver explained.
The best timing for a safety car would have been from lap 28 for Perez, after all drivers leading him had pitted, but even then he was only fifth, some 15 seconds off leader Verstappen.
Perez wasn't helped by a lock-up leading to an excursion in the Rivazza gravel trap on lap 17, which cost him about five seconds. "I also picked up some damage," he added.
Furthermore, Perez suffered from being overtaken by Lando Norris, Oscar Piastri, Carlos Sainz and George Russell on their fresher tyres, while he was eking out his first stint on the hard compound. His pace never recovered – he was often lapping in 1m21s previously but would never do so again until he pitted.
"I wanted to lose as little time as possible [when being overtaken]," he explained. "Unfortunately, at the same time, you are at the end of your stint, temperatures are dropping, and the grip is just very miserable at that point."
Red Bull had a tricky weekend in Imola despite Verstappen's pole position and victory, with the team struggling to find the right set-up in free practice.
Perez said the lack of performance on the Italian track was "a bit circuit-specific" but warned that McLaren and Ferrari "have done a step forward" ahead of the Monaco Grand Prix this coming weekend.
"We expect a very strong McLaren, Ferrari, so it will be a strong challenge out there," he concluded.
Additional reporting by Sam Hall
