Lehmann made the comments after leading Northamptonshire to the Vitality Blast title at Edgbaston, where the county claimed its first trophy in a decade and equalled a record with a third T20 Blast crown. Australians Chris Lynn and Nathan McSweeney played key roles in the triumph, with Lynn top-scoring in the semi-final victory over Somerset before McSweeney's rapid 30 helped Northants post a winning total of 169 against Hampshire in the final.
"I'm so proud of the club," Lehmann told Sky Sports after the 14-run final victory. "We're a little club, little budget, but we play big."
The former Australia coach, who led his country to a 5-0 Ashes whitewash over England in 2013-14 before leaving the role in 2018 following the ball-tampering scandal despite being cleared of involvement, dismissed suggestions he could cross the Ashes divide.
"I'm very happy coaching Northants and I haven't had any phone calls," Lehmann said.
"You'd certainly listen to it. I'm sure there's so many applicants. My feeling is they've already made up their mind. If you remove someone mid-summer, you've got somebody in mind."
Speaking to Cricinfo, Lehmann added: "I'm not sure my wife wants me to spend 300 days a year away again. I haven't spoken to them, so there's no point worrying about it."
Lehmann believes England's decision-makers already know who they want to replace McCullum, drawing on his own experience of replacing Mickey Arthur as Australia's coach shortly before the 2013 Ashes.
Langer has emerged as one of the leading candidates after Andy Flower ruled himself out because of his commitments with Royal Challengers Bengaluru in the Indian Premier League and London Spirit in The Hundred.
The former Australia opener succeeded Lehmann as national coach, retaining the Ashes in England in 2019 before overseeing a 4-0 series win at home in 2021-22. He resigned in 2022 after reports of a deteriorating relationship with senior players.
Should England make an approach, Langer would also need to weigh up his franchise coaching commitments with Lucknow Super Giants in the IPL and Manchester Super Giants in The Hundred.
Lehmann believes his former teammate has the credentials for the role.
"If he (Langer) were to go for it, he'd be a really good coach," he said. "Whoever takes it on, they've got some really talented players. I see some good players in the county system."
Langer is understood to be among several candidates under consideration, with former New Zealand captain Stephen Fleming, ex-England spinner Richard Dawson and former England batter Jonathan Trott also linked to the vacancy.
Trott has received public backing from former England teammates Kevin Pietersen and Matt Prior after impressing during his four-year spell in charge of Afghanistan, where he guided the side to memorable victories over England, Pakistan, Sri Lanka, New Zealand and Australia across ICC tournaments.
England's white-ball captain Harry Brook hopes the coaching situation is resolved before next month's three-Test series against Pakistan.
"You'd like to hope that there'd be a Test coach in place for the Pakistan series, but that decision isn't up to me," Brook told Sky Sports News.
"It's up to the hierarchy and whatever they decide to do going into that series. I'm fully behind whoever they pick, and hopefully it's the right decision."
England smashed the highest one-day international total ever recorded at Lord's before holding off a spirited India chase to secure a 27-run victory and a 2-1 series triumph over the world's top-ranked side.
Andy Flower has ruled out the possibility of replacing Brendon McCullum and becoming England's next Test coach, insisting he is happy with the work he is doing in T20 franchise leagues.
Jonathan Trott, who has been linked with the England Test coaching job, will join the Ireland staff as a consultant ahead of their ODI series against Afghanistan next month.
India made a winning start to the one-day international series with a comfortable six-wicket victory over England at Edgbaston on Tuesday, led by captain Shubman Gill and all-rounder Axar Patel.
