The Premier League leaders restored their eight-point advantage over Manchester United in second thanks to a 96th-minute strike from Raheem Sterling at the Etihad Stadium on Wednesday.
Guardiola celebrated wildly with the City bench after the winner but was seen remonstrating with Redmond on the pitch for some time after the final whistle, as the Saints winger walked towards the tunnel.
However, the former Bayern Munich boss – who had a similar encounter with Joshua Kimmich after a win over Borussia Dortmund in March last year – says he was praising Redmond's quality despite being angered by Southampton's approach in the match.
"I was telling Nathan Redmond how good he is at the end," the City manager told BBC's Match of the Day. "Southampton have some super talented players, Redmond is so good one against one.
"But they didn't want to play, they were time-wasting from the ninth minute. I just wanted them to play."
40 - Man City’s haul of 40 points from their first 14 Premier League games this season is the joint-best tally ever at this stage of a top-flight campaign (also Tottenham in 1960/61 – 3 pts for a win). Momentum. pic.twitter.com/iX3cpGq7aC— OptaJoe (@OptaJoe) November 29, 2017
Oriol Romeu's strike 15 minutes from the end of normal time looked to have salvaged a point for Southampton, who fell behind early in the second half when Virgil van Dijk turned Kevin De Bruyne's free-kick into his own net.
However, Sterling curled home a stunning goal with seconds left to play, leaving Guardiola ecstatic with the effort of his players.
"It was an astonishing end to the game," he said. "It means a lot. They had 10 guys in the box; it was so complicated to attack them.
"They had chances in the first half; all the teams are better than us at set-pieces. They are stronger than us but we kept patient.
"At the end our momentum kept going [and] Raheem scores a fantastic goal.
"What impresses the most is the heart with which they play. What happened in the locker room was amazing. You have to enjoy these situations, you never know what will happen in the future. We want to win the league but you have to celebrate when you score in the last breath like that."