Fernando Alonso insists he is "very happy" at Ferrari amid claims he has approached Red Bull about a move.
With Mark Webber leaving F1, sources say Alonso's manager has told Red Bull that the Spaniard, 31, is potentially available to partner Sebastian Vettel.
Asked whether his representative had approached Red Bull, Alonso said: "I don't think so. Not that I know."
Red Bull boss Christian Horner said there was "quite a lot of interest" from drivers keen on replacing Webber.
He added: "We'll take a bit of time over the summer to reflect on the options that are open to us and look to make the right decision to put the right driver alongside Sebastian before next year."
Kimi Raikkonen and Daniel Ricciardo have also been linked with Red Bull after Webber announced he was quitting F1 at the end of the season.
When it was pointed out that he was not denying double world champion Alonso had approached Red Bull, Horner said: "Any conversations between any of the parties are always going to remain confidential.
"Last week, there was speculation about Kimi. This week, it's about Fernando."
Alonso dropped from second to third in the championship, one point behind Raikkonen, after finishing fifth in the Hungarian Grand Prix on Sunday.
Vettel was third, behind Mercedes driver Lewis Hamilton and 2007 world champion Raikkonen in his Lotus.
Vettel was asked after the race what he felt about the idea of Alonso joining Red Bull.
"I'd prefer Kimi," said the three-time champion. "I have to be careful now, nothing against Fernando. I really respect him a lot as a driver.
"I respect Kimi on track and off track because he has always been really straight with me. From that point of view, it might be a bit easier."
Ferrari insist Alonso has a contract until the end of 2016, with no get-out clauses of any kind, and say he has made no contact with Red Bull.
Ferrari believe claims Alonso has approached Red Bull are mischief-making by their rivals aimed at destabilising the Italian team at a crucial moment in the championship.
"Fernando is an asset for the team," said Ferrari team boss Stefano Domenicali. "First of all, we have a contract with him and for sure everyone knows about it."
Alonso's manager Luis Garcia Abad told BBC Sport there had been "no discussions" with Red Bull.
He said a meeting between himself and Horner on Friday at the Hungarian Grand Prix was to discuss Red Bull junior driver Carlos Sainz, who is also represented by Abad.