Del Piero scored 290 goals in 705 matches for Juve and watched Salah regularly while the Egyptian was playing in Serie A with Roma.
Speaking at the Laureus Awards, the 45-year-old said: "Salah is already a God - and not only in Egypt! When he was at Roma, I remember how many times he was in front of the goal and then he missed the goal.
"And then all of a sudden, at Liverpool he improved that and he scored more than 30 goals per season! When you have this kind of mentality that you want to improve yourself, to grow - it's the best thing."
Salah has scored 14 goals in 23 Premier League appearances so far this season, helping Liverpool to a 25-point lead at the top of the table.
The 27-year-old joined the Reds from Roma in 2017 and has scored 89 goals in 139 matches for the club. body check tags ::