Hornets boss Dyche insisted that Newcastle's bid wasn't worth considering, but Pardew has revealed that it was made in good faith.
"We've tried to be as honest [as possible]," Pardew told BBC Newcastle. "Certainly my philosophy in terms of the media and fans is to get the message out there of what's going on. I don't like there to be surprises.
"Unfortunately in the transfer market it's very difficult because people then come in at the 11th hour. We've had big success in the transfer market just recently and other teams have noticed, it isn't lost on them.
"So when we come in for a player suddenly another club gets interested and the prices start going up. That's something we try to avoid."
The Magpies are believed to have offered around £750,000 for Mariappa's signature.