More than 100 people were arrested and 30 policemen were injured as scores of protesters broke away from an anti-American march here today and pelted Vice President Bush's motorcade with rocks and bottles after ceremonies marking 300 years of German immigration to America.

In a preview of what West German authorities fear may be a "hot autumn" of demonstrations against nuclear weapons, about 1,000 youths, many of them in "punk" attire, marched through the streets bearing signs that read "Bush Go Home" and "USA, Hands Off Nicaragua."

Speeding back to their hotel from a downtown auditorium, Bush and his entourage were intercepted near the railway station by protesters who began hurling objects before being chased back by helmeted police holding shields and wielding truncheons.

Several limousines were dented, and a bus window was broken, but no one in the motorcade was injured.

West German Chancellor Helmut Kohl apologized to Bush for the incident and assured him that the West German government "will not bow to terror in the streets" when the time comes to deploy new nuclear missiles here later this year.

Kohl's spokesman, Peter Boenisch, quoted the chancellor as telling Bush, "Unless there is a miracle at the Geneva arms talks , and I don't see one happening, we will have to deploy the missiles and we intend to do so."

Kohl, who plans to visit Moscow July 4, told Bush that his trip will show whether the Soviet Union "is betting on and possibly overestimating resistance in the streets," the spokesman said.

Many residents of Krefeld expressed outrage and embarrassment at the violence, The Associated Press reported. "I think they should all be taken away," said Hans Kuhlkamp, the owner of a tavern caught in the hail of rocks and bottles. "It just doesn't make sense to me."

Bush appeared to regard the stoning with equanimity and joked in a luncheon toast that running the gauntlet of demonstrators reminded him of "Chicago in 1968"--a reference to the clashes of police and antiwar protesters at the Democratic National Convention.

Bush later continued his European tour by flying to Norway.

Bush reportedly told Kohl that the Reagan administration harbors no doubts about the reliability of the Bonn government in carrying out its commitments to deploy the first batch of 108 Pershing II missiles in December if arms control negotiations in Geneva fail to achieve a compromise.

Government officials here fear that the missile deployments may discredit the nonviolent tactics of the peace-minded wing and embolden a minority to increase the use of violence and terrorism.

In his weekly radio address from Washington yesterday, President Reagan called on young people "both in Germany and in America" to recognize "all that we are doing to deter and to reduce the risks of war."

The rock-throwing attacks on the Bush motorcade contrasted sharply with a peaceful rally nearby for 15,000 antimissile partisans.

Two leaders of the antinuclear Green Party, Petra Kelly and Gert Bastian, strongly deplored today's assaults in the streets and denounced those who participated as enemies of the peace movement.

"They were punks, that's all," said Kelly. "The stone throwers have nothing to do with us."

Bastian, a former general turned pacifist, was applauded when he told the large, peaceful rally that all protests must employ nonviolent methods "like those used by Martin Luther King."

Bush's one-day visit here commemorated the departure from Krefeld of the first 32 German migrants to America three centuries ago. They established a settlement near Philadelphia.

Peace movement leaders said they staged the protest rally to draw attention to the fact that the first migrants, Quakers and Mennonites, were pacifists who sailed to the new world seeking religious freedom. During his speech at the Krefeld ceremonies, Bush avoided any mention of missiles and dwelt on the close cultural bonds linking Germans and Americans.

In his speech, Kohl said that 51 percent of West Germans now consider the United States their best friend.

He dismissed signs of anti-Americanism as "more written about than spoken."