However, Ibrahimovic, still playing at 40 with AC Milan, accused 22-year-old Mbappe of being in a "comfort zone" at the French club.
"I love Mbappe, but what he is doing is not enough. He is too comfortable, he is in his 'zone'," the Swedish player told French TV programme, Telefoot, on Sunday.
"He needs to walk on fire and if he walks on fire, he will be even better," added Ibrahimovic, who played at PSG from 2012-2016.
"Imagine how strong he could get if he hurt himself. He has to taste the taste of blood. Surround yourself with those who tell you that you are not good enough and that you have to get better, and you will get better."
Mbappe has scored five Ligue 1 goals so far this season as PSG threaten to run away with the title.
However, he endured a difficult summer, missing the penalty which knocked world champions France out of Euro 2020 at the last-16 stage and then being at the centre of a transfer saga which saw his desired move to Real Madrid denied by PSG.