Asked if he took his comments from the weekend too far, Guardiola replied: "With their statements, they defend each other, \[that is\] completely understandable. They have to do that.
"But at the same time I have to defend my club. How many times did I criticise the referees last season, which was the worst season in 10 years? How many times?
"If he is offended then I am so sorry. I know it's not easy on debut - and it's happened. Everyone is so sensitive, I know that."
Following the match, Guardiola said he would be awaiting a call from referees' chief Howard Webb to "explain why it is not a penalty".
For the third time in two weeks, Webb was again referenced by Guardiola in a news conference as he added: "Never, ever, in 10 years I have criticised the referees. What I am saying this season is arguments and reasons why we have done it.
"I defend my club and my players. Howard Webb defends the referees. He has to do that.
"Look what happens in the boxes from corners and free-kicks: every action, it is not easy. Every action is a foul, every action. I know it is not easy, but I have to defend my club and my players for many reasons."