Carlos Tevez opened the scoring for City late in the first half and David Silva and Vincent Kompany also got in on the act, before a James Perch own goal completed the rout.
City look destined to finish second in the table and Pardew believes their situation means they will be formidable opponents for the rest of the season.
However, the Newcastle manager also recognised that his players were below their best as they slumped to a heavy defeat which leaves them just three points above the relegation zone.
"It looked like they weren't under any pressure, you could almost sense it," Pardew told Sky Sports.
"They were very relaxed and that is very dangerous when you have great players like they have, playing without any fear.
"But having said that, in the first half we didn't put enough pressure on them or technically keep the ball as well as we have done in previous games.
"Therefore you are asking for trouble, and we certainly got that today."