The teenager eased PSG nerves with an unstoppable 77th-minute strike to put the champions back in front after the hosts had battled back from two-goals down and then hit the crossbar.
Mbappe brought down a high ball and without breaking stride, belted a shot into the roof of the net.
With seconds remaining, however, Mbappe reacted to a late challenge from Teji Savanier and shoved the Nimes midfielder to the floor. Referee Jerome Brisard, who booked Mbappe for kicking the ball away in the first half, brought out his red card. Savanier was also sent off.
The teenager said he had no regrets after his sending-off and claimed he would not hesitate to do the same thing again.
The 19-year-old striker’s reaction was in retaliation after he had been scythed down by Savanier
“No, no, no,” said Mbappe afterwards when asked if he wished he had not responded the way he did.
“If I had to do it again, I would and I would apologise to all the supporters and to everyone.
“I cannot tolerate that sort of gesture, it doesn’t belong on a football field. It wouldn’t be a problem if he intended to play the ball, but he made no attempt to play the ball, we all saw it.
“But it doesn’t matter, I’ll go and defend myself before the disciplinary committee.”
Mbappe will now be automatically suspended for PSG’s next game, a home match against Saint-Etienne on September 14 that precedes a trip to Liverpool in the Champions League.
But the nature of the offence means he could face a lengthier ban from domestic action.
Prior to that, Neymar had opened the scoring and Angel Di Maria doubled the PSG lead by scoring direct from a corner.
But Nimes responded in the second half and Antonin Bobichon halved their deficit before Savanier equalised from the penalty spot in the 71st-minute after a spot-kick awarded with the assistance of VAR.
It was Mbappe’s 77th-minute goal that punctured the home side’s hopes, before Edinson Cavani secured the win late on to leave PSG with maximum points after four games of the Ligue 1 season.
Asked if he doubted that PSG would win all three points, Mbappe said: “No, we want to be a great team, and a great team must learn never to doubt itself, even in difficulty. We were in a lot of difficulty today but we come away with the victory.”
Maxim Choupo-Moting has joined French champions Paris Saint-Germain on a free transfer after having his Stoke contract cancelled, the Potters have announced.
The 29-year-old Cameroon international was part of the City side which was relegated from the Premier League at the end of last season, but will now have the opportunity to play Champions League football during the new campaign.
A statement on Stoke’s official website said: “Maxim Choupo-Moting has joined Paris Saint-Germain on a free transfer after his Stoke City contract was cancelled by mutual consent.
“The Cameroon international made 32 league and cup appearances for the Potters after joining the club in the summer of 2017.
“The club would like to take this opportunity to thank Maxim for his efforts and wish him well in the future.”
✍️🎙 Our first interview with Eric Maxim Choupo-Moting 🇨🇲 pic.twitter.com/WMoobakRp9— Paris Saint-Germain (@PSG_English) September 1, 2018
Hamburg-born Choupo-Moting arrived at the bet365 Stadium from Schalke in August last year and scored both goals in a 2-2 home draw with Manchester United the following month.
He scored three more times, with his last coming in his final Stoke appearance in March, when City lost 2-1 to Everton.
Choupo-Moting told his new club’s website: “I am extremely honoured to be signing for this big European club.
“I will be playing with some extraordinary team-mates and I can’t wait to experience the atmosphere at the Parc des Princes.”
Thilo Kehrer had a debut to forget for Paris Saint-Germain in their 3-1 win over Angers on Saturday, but boss Thomas Tuchel is still high on the young German.
The 21-year-old conceded a penalty to Angers before being replaced at the break, bringing an end to a less than stellar first outing for a talent who commanded a €37 million price tag in the summer.
“It’s a bit miserable for him, but it’s not a problem because it’s important that he adapts to a new system and I remain confident in him. He will improve.”
See Tuchel’s full comments on Kehrer in the video below.