Beattie scored five goals in 15 appearances for Palace during a loan spell earlier in the season before returning to West Bromwich Albion.
Warnock had been keen to bring the striker back to Selhurst Park, but Football League rules mean Beattie would only be able to return for just over a fortnight.
The situation has led Warnock to confirm that any attempt to capture Beattie, who is currently recovering from a groin injury, would be futile.
Pointless"We've already had him for 70-odd days, so we can only have him for around another two weeks, which is pointless really - so that's dead in the water now," Warnock told the Croydon Advertiser.
Meanwhile, Warnock has revealed he is willing to loan out James Scowcroft and Carl Fletcher when the transfer market restarts next week.
He added: "Now the transfer deadline has passed, we will consider loan moves for a number of players, including Carl and Scowy."