Manchester United manager Jose Mourinho insists he is "not surprised" Pep Guardiola avoided punishment for encroaching onto the pitch during Manchester City's win over Southampton despite being sent off for a similar offence earlier this season.

Mourinho was sent to the stands during United's 1-0 over Southampton in September after briefly stepping over the touchline in the final minutes.

Guardiola, though, was let off with a warning from referee Paul Tierney after his wild celebrations on the pitch following Raheem Sterling's stoppage-time winner at the Etihad Stadium on Wednesday.

Asked at a news conference on Friday whether he was surprised at the lack of consistency, Mourinho, who did not receive a touchline ban after his sending off at St Mary's, said: "Surprised? No. Not surprised."

The United manager has suggested in the past he is held to different standards than other Premier League managers.

Pep Guardiola's wild celebrations bled onto the pitch after Raheem Sterling's stoppage-time winner on Wednesday. Getty Images

But asked to clarify why he was not surprised, the 54-year-old declined the opportunity, adding that he did not want to land himself in trouble with the FA.

He said: "You are asking me one question, if I am surprised. I say I am not surprised. The second question is nothing. It's another one.

"I can't answer to the second question.

"You know, if you are my friends, don't ask me the question, because you know I get into trouble, so no."

The FA have, however, asked Guardiola for his observations after the Manchester City boss was involved in a heated exchange with Southampton winger Nathan Redmond after the final whistle.

Redmond took to Twitter on Thursday night to brush off the conversation as "positive and complimentary" although Guardiola admitted on Friday he regrets his actions.

Asked whether he thought the Spaniard's actions in confronting Redmond were "strange," Mourinho again declined to comment.

"Don't ask me that," he replied.