President Bush apologized today for the deaths of two Korean girls hit by a United States military vehicle in June, an incident that has led to angry anti-American demonstrations.

The apology to the girls' families, the South Korean government and the Korean people, delivered by the American ambassador here, was in response to a demand of protesters outraged first by the girls' deaths and then by the dismissal by a United States military court last week of negligent homicide charges against the two sergeants in the vehicle.

The ambassador, Thomas Hubbard, did not say why Mr. Bush had waited until now to make the apology, a demand not only of demonstrators but also of candidates in the Korean presidential election next month. At a news conference today, he and Gen. Leon LaPorte, commander of the 37,000 American troops in South Korea, combined their own profuse apologies with a defense of the justice system under which the soldiers were acquitted.

''President Bush, who has visited Korea and has a special feeling for the Korean people, has been touched by this tragedy,'' said Mr. Hubbard. ''Just this morning, the president sent me a message asking me to convey his apologies to the families of the girls, to the government of the Republic of Korea and to the people of Korea.''