The McLaren driver was around five seconds behind race-leader Max Verstappen early in the race when the VSC was called out because of debris on the track after Perez had collided with Haas driver Kevin Magnussen.
As Norris approached Spoon Curve, he closed in on the very slow Perez, who was returning the pits to get his car repaired.
However, unsure about whether or not Perez had a problem, he had to back off to avoid the risk of getting a penalty for overtaking the Red Bull under the VSC.
That allowed Verstappen to pull out a further five-second advantage, which made the Dutchman’s life easier at the front of the pack.
Norris said that, amid uncertainty about what Perez was up to, he could not risk the pass – so had to slow and see valuable seconds slip away.
Asked by Autosport what happened at that moment, Norris said: “I don't know what… he must have had a problem, right?
"But the thing is you can't overtake under the VSC unless it’s obvious the guy has a problem. I didn't know if he had a problem, or whether he was just backing me up. I didn't know and I couldn't take the risk of just overtaking him.
“He was going so slowly and then when we get the flashing dash for the VSC ending, he went into first gear and then I was on the outside of him because he was going so slowly, and then he almost crashed into me. So, I honestly have no idea.
“I was shouting in my helmet. I was swearing quite a bit, but I was so confused. I didn't know what I could do. I'm losing time to Max. The Ferrari guys were, I think, 1.4 seconds behind me after being I think 12s or 13s, so I lost 10 seconds. And I didn't know what I could do at the time.”
Source: Autosport