Lille won 2-1 away to Angers on Sunday to clinch the Ligue 1 title, having come into the final day one point ahead of second-placed Paris Saint-Germain.
PSG did their part, winning 2-0 away to Brest, but it wasn’t enough, leaving Pochettino disappointed for a club who had won the past three Ligue 1 crowns.
“Of course we are disappointed, we really believed that anything could happen in Angers, but it didn’t happen,” he said.
“I think we were professional and we won. But in the end, it wasn’t enough to win the title. We are disappointed and really sad.”
Pochettino pointed to PSG’s hectic schedule in 2020-21, playing 57 matches in four competitions, barely without a break after participating in last season’s Champions League final too.
“We were playing every three days and we made it to the semi-finals of the Champions League, beating Bayern Munich and Barcelona,” he said.
“We won the Trophee des Champions and the Coupe de Franc, which was important for the team. But Paris Saint-Germain will always be disappointed when finishing in second.
“We need to use the experience for the future of the club and of course to change things. It’s important for the club to improve and we believe that we can get better. We are going to work hard for that to happen.”
PSG’s superstar Kylian Mbappe had said in October: “For me, and there’s a lot of us that feel this, it’s not a new season. It’s as if last season were still going on. For me, it’s the 60th match of the season, and not the ninth of the new campaign.”