The Bluebirds were pegged back by Derby County in Tuesday night's rescheduled match at Pride Park, losing 3-1 to remain just one point above third-placed Fulham.
Cardiff will face Hull City away in their next game before hosting Reading on May 6 for their last regular league fixture of the season.
"There is no two ways about it, we need to win two games," Warnock told BBC Sport. "All you can do is your best, and that's all I have asked my players from day one.
"To get 86 points in the situation we were in is amazing. If you said to me on July 5 when we started training, 'you need to win your last two games to get promoted', I would have snapped your hands off.
"You just don't know in the league, anyone can beat anyone, you don't know what's around the corner."
Fulham, meanwhile, play already-relegated Sunderland in their next fixture on Friday night before travelling to Birmingham City on the final day of the season.