The forward became Liverpool's youngest-ever goalscorer at the age of 17 years and 45 days after scoring in front of the Kop in the 2-0 EFL Cup victory over Leeds on Tuesday.
"I want to congratulate him. He is a very good player and has a very good future," Mane said. "I hope he will keep going and working hard and I think he will be a great player.
"Everyone was happy for him to score his first goal, especially in a big atmosphere at Anfield."