The Egypt international has been in scintillating form for the Merseyside-based outfit this season, scoring 31 goals in 33 league appearances and just over 40 in all competitions under Jurgen Klopp.
Salah was on Sunday named the PFA Player of the Year, becoming only the seventh Liverpool player to win the accolade.
"It is early to compare him with Messi," Pienaar told KweséESPN.
"But he's tough and he's got the character to build on. I think he can be consistent for many, many years, and he's only young as well," said the former Bafana skipper.
Pienaar said he knew the first time he saw Salah in action during his days at Basel that he was a special player.
Salah moved to Italy to join Fiorentina and later AS Roma after just a season-and-a-half with Chelsea, and his impressive performances caught the eye of Klopp, who brought him back to the Premier League, and the left-footed attacker is no doubt a better player than the one that left England in 2016.
"When I first saw him at Basel, I knew there was something special about him. Back then, they said he was the Egyptian Messi who was going to come through, and when he moved to Chelsea he was just unlucky that he didn't get the opportunity that he's getting now," added Pienaar.
"When he left, he went to Fiorentina to work on his confidence, and I was never surprised. He's just showing what he can produce if you give him an opportunity to play. He's the first African player to score  goals for Liverpool. So, he's a special player," concluded the former Tottenham Hotspur midfielder.
Since his return to the Premier League at the start of the season, Salah has broken several records, including that of Didier Drogba, who until not so long ago, was the only African player to have scored 29 league goals in one season.