"He was very excited to start a match. He's an emotional player, he likes to play, he likes to fight, he's a competitor. He didn't deserve that red," Pochettino said.
That loss saw PSG drop to second place in the domestic standings to Lille, but Pochettino added that he expects Neymar to be focused for Wednesday's European match.
"He knows he has to channel himself. I hope that tomorrow everything will be fine," Pochettino said.
Pochettino added that his side will not have revenge on their minds against Bayern after losing to the German team in last season's final.
Bayern beat PSG 1-0 in the final last year to seal a Treble but Pochettino, who replaced manager Thomas Tuchel midway through this season, said this time would be different as they were playing a two-legged tie.
"The final is not a benchmark match for us, we weren't there with my staff, we were just spectators," Pochettino said ahead of the first leg in Munich.
"In addition, it's going to be played over two matches, the context is different. Revenge exists in sport but for us it's more of a challenge to beat such a strong team, maybe the best in the world. It's a source of motivation."
Both sides will be missing key players, with PSG striker Mauro Icardi out with a thigh injury while midfielder Marco Verratti and his Italy teammate Alessandro Florenzi both tested positive for COVID-19.
Bayern striker Robert Lewandowski is sidelined with a knee injury while winger Serge Gnabry tested positive for COVID-19 but Pochettino said the German league leaders had enough squad depth to remain competitive.
"The strength of Bayern is in its collective," Pochettino added. "When you win the Champions League and the Club World Cup, it's because you have a very good group, not just 11 performing players."
Reuters contributed to this report.