Welbeck was barged and tripped by Phil Jagielka in the 68th minute and even Jagielka admitted there was contact.
Welbeck said: “I was barged on my left-hand side and as I went down I was caught on the leg as well.
“I had no reason just to go down because if I had not been fouled I would have scored — I was round the keeper.
“I’m disappointed to lose. We should have won even without that penalty because we were the better team.”
Jagielka said: “I touched him, but I’m not sure how much that caused him to go down. Thankfully the penalty was not given.
“Maybe that was a bit of luck but we will take that.”