Goals during the opening quarter-hour from Dilan Zarate (penalty) and Pietro La Torre gave the Italian team control.
An unfortunate Kornel Misciur own goal was followed by Mattia Mosconi and Kevin Moressa finishes late on.
The Reds had, though, already secured their spot in the next stage, with this the final fixture of the league phase.
Inter were awarded a penalty within a minute of kick-off at Konami Youth Development Centre.
It was given somewhat harshly against Lucas Clarke for handball inside the box, and Zarate stepped up to guide the ball past Misciur to the left.
The hosts might have made it two soon after, too. Mosconi got into space down the right and moved in towards goal to shoot, but his arcing attempt was sliced wide.
They did double their lead on 14 minutes, though, and in stunning fashion.
A corner kick from the right-hand side was clipped outside the box to La Torre, who chested it down and smacked a half-volley inside the left post.
Liverpool could have responded quickly, creating an opening from a possession steal in the opposition half.
Keyrol Figueroa squared to Trent Kone-Doherty across the Inter area, though the forward’s low finish was too close to the goalkeeper.
After an uneventful spell, the Reds gained a huge chance to hit back from the penalty spot. Kieran Morrison dribbled down the right and his cross struck the arm of Mattia Marello.
The referee pointed to the spot once more. However, Morrison’s attempt from 12 yards clattered the base of the left post and went out.
Morrison was then denied by the legs of Inter goalkeeper Matteo Farronato with a driven shot, and from the resulting corner Emmanuel Airoboma was off target with a free header at close range.
Misciur made a comfortable low save after Aymen Zouin broke free left of goal and tried to find the far corner.
A frantic end to the half saw Alvin Ayman clear off the goalline to thwart another Zouin effort.
