Zaha is reported to be nearing a loan move to Cardiff City this month after enduring an indifferent start to life with United, with the 21-year-old making just two Premier League appearances all season.
Rumours of a worsening working relationship with Red Devils manager David Moyes surfaced during the week after the winger reportedly turned up 45 minutes late to a reserve fixture.
Holloway, who worked with the youngster at Selhurst Park in Palace's promotion to England's top flight last season, has urged his former player to take stock of his career before it is too late.
"I was surprised by reports during the week that he had been dropped to the bench for a reserve game because he turned up late," he wrote in his column for The Mirror.
"That isn't the Wilfried Zaha I know and I am sure that he would not have shown such a lack of respect to his club on purpose. And, again, it's all about attitude. Or lack of attitude.
"I will always be grateful to Wilf for the role he played in helping Palace to win promotion to the top flight when I was the manager at Selhurst Park. And that's why I have his best intentions at heart when I say the time has come for him to take stock of his life and career and grow up a little bit. Because, believe me, there is nothing more tragic than unfulfilled potential."
Zaha has made just four appearances in all competitions for United this season.