The prequel, set to open worldwide in May 2009, explores how the starship Enterprise and its iconic crew set out on their interstellar journey, adding a good dose of space battles and dastardly aliens.
"My goal was to make a movie about the emotional lives of these characters," Abrams told reporters. "We've seen a million ships fly by the camera, but nobody is going to care about the ship if they don't care about the people inside."
Abrams hopes the movie, which is aimed at revitalizing the 42-year-old franchise, will appeal not only to die-hard fans but to people who didn't follow the original 1960s adventures of Kirk, the logical alien Spock and their fellow explorers.
"I want fans of Star Trek to come watch it, but the truth is I made the movie for future fans," Abrams said at the presentation in a Rome theater. He and his footage made similar appearances across Europe this week.
"Star Trek" fans - and they are legion - have been eagerly anticipating the movie for more than a year. As excited as they are, however, many have expressed trepidations that the film will be a "reboot" and will reconfigure the fictional history of the "Trek" universe they have followed so ardently.
Abrams and his writers have promised to be faithful to the spirit of "Star Trek" and its fan base. Still, the director of "Mission: Impossible III" and creator of TV's "Lost" and "Alias" acknowledged that he was no Trekkie before starting the project.
"It was never my thing," he said. "I have become a trekker having fallen in love with the characters."
The preview and four "Star Trek" scenes were strictly controlled, with security keeping out cameras and other recording devices.
This much we can say: The brash and womanizing Kirk had a less than glorious start to his career, since the film introduces him as a bar-brawling biker in 23rd-century Iowa.
The movie follows the young troublemaker, played by actor Chris Pine, as he meets up with his future crew, getting off to a rocky start with most of them, including Zachary Quinto's edgy and hostile Spock.