The forward also said he was disappointed not to be made captain for Liverpool's Champions League clash against Midtjylland earlier this month.
Aboutrika, who played 100 games for Egypt, said Salah was unhappy at Liverpool.
"I called Salah about his situation in Liverpool and he is upset, but that would never affect his performance on the field," he told beIN SPORTS.
"I know that Salah is not happy in Liverpool, he told me the reasons why he is not happy but they are secrets and I cannot talk about it in public. One of the reasons that made Salah angry that he was not the captain against Midtjylland."
Salah joined Liverpool from Roma for a reported £36.9million (€42m) in mid-2017.
Aboutrika believes the Premier League champions are thinking about selling the 28-year-old forward.
"In my opinion, Liverpool is considering selling Salah for economic purposes," he said.
Salah has scored 110 goals in 173 career appearances for Liverpool, including 16 in 21 this season.
He has helped the club win the Premier League, Champions League, UEFA Super Cup and Club World Cup.