Palace had been linked to Smith but Warnock made no effort to confirm any link.
He told the Croydon Guardian: "I think he might have been the lad that was recommended to us but I am alright for left-backs now."
The manager did admit that the Eagles were currently looking at three players who were spending the week on trial, including Wakefield Town's Marc Roberts.
He added: "He is in training with us for a week and we are getting a look at him.
"We look at a lot of lads though and we've also got two others on trial as somebody asked us to have a look at them and it doesn't cost us anything."