Mercedes rival Toto Wolff claimed however that Red Bull had been under investigation for months and it was an open secret in the paddock that one team was in massive breach of the budget cap.
"Maybe he doesn't speak to his CFO," the Austrian told Sky Sports television.
Horner told the broadcaster earlier at the Singapore Grand Prix that none of the 10 teams had so far received a compliance certificate.
"There’s an awful lot of rumours and gossip and we know where most of that permeates from," he said, without naming anyone.
"There’s a lot of conjecture about Red Bull but that could well be about four or five teams in the pitlane."
According to media reports, Red Bull and Aston Martin exceeded the mandatory $145 million budget cap imposed on each team in 2021.
An Aston Martin spokesperson said the team were "in discussion with the FIA, and we are awaiting certification (of the data)."
There was no official confirmation of any breach, with the governing FIA saying it was still assessing the financial data submitted by teams and would proceed according to the rules.
Horner said certificates were due to be issued next Wednesday, although the date had been changed three times already.
"They are following their process. Let them do their process and then let’s see what comes out. Anything before that is just speculation," he said.
"It’s the first year of these regulations, accounts were submitted in March. There’s been clarifications since March on certain aspects of what and how things can be submitted and these regulations are still very, very immature.
"They (the FIA) are taking their time to do the job properly and we’re very confident in the submission that we’ve made. So I wouldn’t listen to too many idle bits of gossip and rumour."
Wolff, whose seven times world champion Lewis Hamilton fought Red Bull's Max Verstappen to the last lap of the final race in 2021, said at least two teams were in the spotlight.
"As far as we understand there is a team in minor breach, which is more procedural, and another team that is fundamental and massively over," he said.
"The rumour mill is going since a while that they are over and they are quite a lot over."
Formula One introduced the budget cap last year, narrowing it to $140 million this year and $135 million next season, to rein in runaway spending by the biggest teams and level the playing field.
Possible sanctions range from fines to exclusion from the championship.
Williams were fined $25,000 this year for a procedural breach of the financial regulations after missing a deadline to submit their accounts.
Red Bull finished second behind Mercedes in the constructors' standings last season.
Verstappen could win his second title this weekend in Singapore.
