Guardiola's bid to buy Sanchez collapsed at the end of the summer transfer window and City were favourites to land him this time around but the club are apparently unwilling to meet Arsenal's reported 35 million ($48 million, 39 million euros) asking price.
Mourinho's United are understood to have thrown their hat into the ring, bidding around 25 million to trump City's 20 million offer as they seek to bolster their forward options and deny their bitter rivals.
Questioned as to whether there was any truth in the rumour, the Arsenal manager was coy.
"You conclude that," he said. "You could say that at the moment... it's not that I don't want to inform you, I don't want to give you wrong information and at the moment I must say nothing is decided one way or the other."
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Wenger admitted a bidding war could help Arsenal but said that was not the current situation.
Guardiola said his focus was on maintaining City's fine form when they travel to Liverpool in the Premier League on Sunday.
"I understand completely why you ask this question (about Sanchez), it's your job," said Guardiola. "But you know my answer. I am focused on Liverpool."
Mourinho, who described Sanchez as a "phenomenal player", said: "I don't know if it's ethical or correct to be speaking about players of other clubs."
"Sanchez is an Arsenal player," he added. "Probably this weekend he is going to defend Arsenal colours so I don't think it's correct to say things about Alexis Sanchez."
"Of course I want a quick resolution," he told reporters at Arsenal's north London training base.
"Is he (Sanchez) replaceable in the way that we find exactly the same player? Certainly not, but there's always a way to find a different balance.
"Alexis is an exceptional football player, he's a world- class player and if that happens (and he leaves) we have to find a different balance in the team."
Wenger said he does not want the 28-year-old to leave, but conceded he cannot guarantee the forward playing time and an unlikely route into Gareth Southgate's England squad for the World Cup.