Perez has now failed to make Q3 at three consecutive events, the streak having started with a qualifying crash at Monaco that led to a scrappy race and no points in the principality.
In Spain, he recovered well from 11th on the grid to fourth after a solid race, and while in Canada his run from 12th to sixth was respectable it was evident that he didn't have the pace that he expected to have on race day.
"I think he just needs a good weekend to just lift his confidence," said Horner when asked what the team could do to help him.
"I think he's had three difficult weekends, three difficult Saturdays, that then puts you on the backfoot on a Sunday. And we've seen what Checo is capable of, only a month or two ago.
"And I think he just needs to have a strong weekend to find that confidence. And then I've got no doubt he'll be back."
Horner downplayed any suggestion that Perez's future with the team might be under threat.
"He is second in the world championship at the moment. He's the only other driver to have won two races other than Max this year.
"So yeah, we need to support him through this period. And I'm sure he'll find his form again soon."
Perez, who said he felt uncomfortable under braking in Canada, agreed that he has to work things through with his engineers.
"Yeah, certainly we're going to be working hard, together with the team back home, to make sure that we figure out what's happening at the moment," he said when asked about his struggles by Motorsport.com.
"I mean, it is how it is. But I think it's something that mentally you have to be strong. And I'm strong.
"And I know I will overcome this one, this difficult period of basically two races because Monaco, I did the mistake and it was a bad weekend. But I think without that we had the pace, and it's a little bit more concerning not having the pace."
