The Newcastle United boss picked up his first point in charge on Sunday, a dramatic 2-2 draw with Liverpool at St James' Park, though the result was soured by Hall conceding a stoppage-time penalty that allowed Dominik Szoboszlai to rescue a point for the visitors.
Newcastle had twice led through Anthony Elanga and substitute Joe Willock before Hall's 96th-minute foul on Victor Muñoz proved costly.
Speaking on Sky Sports afterwards, Jaissle took pride in his side's performance despite the late setback.
"Hard luck, I would say. I'm really, really happy with the performance after such a short amount of time. The guys were fighting till the end, they put their heart on the pitch and this is something we said that's not negotiable.
"That's the standard. And together with the crowd, it was, in general, a really good performance. Unfortunately, we couldn't get the full three points."
Discussing his plans for the remainder of the transfer window, Jaissle admitted more business was likely.
"I think it will be a stressful period for the sporting director. We have some needs, definitely."
Pressed on where reinforcements might arrive, he began to answer before catching himself: "Position wise…" prompting Schmeichel to laugh and press him further.
"You can tell us," the United great said. Jaissle replied: "Because you ask, I was about to tell you but I will keep it a secret."
He added: "If you are bringing players in, maybe there will also be some players out."
Schmeichel then suggested Newcastle's left-back position could be one to watch, telling Jaissle: "We're looking at your left-back."
The Newcastle boss gave the idea short shrift, jumping in with a grin. "No chance! No chance!"
Hall, subject to persistent transfer speculation in recent months and left out of England's World Cup squad this summer, had been one of Newcastle's standout performers before his late error, setting up a strong chance for Yoane Wissa earlier in the game with a driven low cross.
Jaissle's comments leave little doubt that, whatever else changes at St James' Park before the deadline, the England left-back is not for sale.