On Wednesday the Reds confirmed the arrival of the 23-year-old Hoffenheim forward in a deal which will see them pay £22million up front with the rest due in add-ons.
It makes the Brazil international the club's second most expensive signing after £35million flop Andy Carroll and Babbel believes that brings a certain degree of expectation.
"That is brutal," he told German newspaper Bild.
"When I heard that I flinched, because even for Liverpool that is not chicken feed.
"He is under a certain pressure with this weight on his shoulders."
However, despite his concerns over the size of the fee, the former Germany international, who was at Anfield between 2000 and 2004, believes Firmino will be well-suited to the Premier League.
Babbel thinks spending his formative years playing four seasons in the Bundesliga has provided the idea platform for the Premier League.
"He is an atypical Brazilian, more German than many Germans. Roberto is disciplined, has enormous assertiveness," he added.
"Roberto does not complain when he is fouled. He is not an actor, he stands up again. That is beneficial in England, because that is what English fans like to see."
Source: PA