Voldemort trying to get the stone from Harry Potter:
Voldemort: Together, we'll do extraordinary things. Just give me the Stone!
Harry Potter: (yelled) You liar!
What made Harry Potter yell, "You liar!"?
In the original script, Voldemort promises to use the stone to restore his parents to life. Harry sees through this ruse and calls him a liar.
[Harry stops, looks up. Quirrell steps aside, Voldemort's face sliding from the glass and revealing...Harry's parents]
VOLDEMORT: Together, we can bring them back. All I ask...is for something in return.
[Slowly, almost involuntarily, Harry removes the Stone from his pocket.]
VOLDEMORT: That's it, Harry. There is no good and evil, there is only power, and those too weak to seek it. Together, we'll do extraordinary things. Just...give me the Stone.
[Harry studies his parents' faces, drifting to his mother's, when...we RACK FOCUS...and Voldemort's hideous face surfaces through her's...and she is gone.]
Interestingly, in the original novel Harry is calling Voldemort a liar for insisting that his parents had died begging him for mercy.
So he knew. The feeling suddenly surged back into Harry’s legs. He stumbled backwards.
‘Don’t be a fool,’ snarled the face. ‘Better save your own life and join me … or you’ll meet the same end as your parents … They died begging me for mercy …’
‘LIAR!’ Harry shouted suddenly.
The book is different from the movie. This analysis is for the movie ONLY.
"Harry, would you like to see your mother and father again?"
The Mirror of Erised hints that Voldemort is lying about his proposal to help resurrect Harry's dead parents (whom he killed, by the way), through the vanishing faces of Lily and James.
This symbolizes that they can't be brought back – foreshadowing that even the Resurrection Stone is illusory – and even if it were possible, Voldemort has no intention of bringing back OotP members; rather, he'd opt to bring back fallen Death Eaters from the FWW.
"There is no good or evil; only power and those too weak to seek it. We could do extraordinary things..."
This is a crucial inflection point in Harry's growth that leads him to be different from Voldemort [despite their many similarities imprinted onto Harry]. It may be the first important ethical decision he needs to make throughout the series (other than befriending Ron instead of Draco?). Voldemort offers false promises, and a false ethos and narrative; Harry is smart and just enough – even at 11 – to perceive these as deceptions and to resist temptations. The mirror simply gave him a quick clue, as it is itself programmed to reflect false depictions of wizard and witch's desires, and (this is speculation) possibly doesn't entertain competing visions from proximate lying wizards/witches. It's for Harry to make decisions based on this information.
The narrative that Voldemort wants to instill in Harry is that the conflict between good vs. evil doesn't exist, when that is not the case, as made abundantly more clear in the later books/movies. He offers false compacts and this narrative, because it's easier and safer for him to persuade or coax Harry to give him the Philosopher Stone willingly than to risk a second destruction from the identical person almost 12 years earlier.
Most answers have already pointed out that it's in response to Voldemort saying that he can bring his parents back if Harry gives him the Stone.
However, the answers do not say why Harry would see this as a lie, since obviously this is one of Harry's biggest desires.
This is not based on any credible sources, but... I think it might be because a bit earlier in the film, when Dumbledore catches Harry in front of the Mirror of Erised, he says "No power can bring back the dead. I trust you know this?".
Harry trusts Dumbledore more than anyone, so it might not be that far-fetched that this is why Harry screamed "Liar!" when Voldemort said he could.