The 29-year-old admitted he was "quite disappointed" after his chipped spot-kick was saved by Kelvin Davis.
"It's three points and a little headache for me," Van Persie told Sky Sports and MUTV. "I don't know what I was thinking with the penalty, I wanted to hit it hard like I always do but at the last second I changed my mind, somehow. That wasn't good enough so that was a bit of a down. I'm quite disappointed to be fair. I ask a certain standard from my game and when something like that happens, when you're 2-1 down, you can't take a penalty like that.
"It is me who is to blame. I don't know what went wrong but something went wrong big time, so I have to work on that. After that I was very relieved that we got the three points, trust me."