A group of journalists, scholars and military men called on President Reagan and other leaders yesterday to assure that news organizations be permitted to cover war zones without undue restrictions.

In a 164-page report issued in New York, the group added that members of the military and the media are bound to clash because of a "cultural divide" that separates them.

The report, entitled "Battle Lines," was produced after a 10-month study by the Twentieth Century Fund's task force on the military and media. It recommended that government officials and representatives from news organizations negotiate arrangements for access to battle zones rather than rely on the courts.

The task force found that there was no military justification for excluding reporters from the U.S. invasion of Grenada in October 1983. Shortly afterward, the Defense Department established a pool of news representatives who would be mobilized to cover secret military operations.

"The presence of journalists in war zones is not a luxury, but a necessity," it said. The report said that the relationship between the media and the military has always been adversarial but that since the Vietnam war, it has become hostile.

The presence of journalists, it said, can be assured through clear guidelines for media access, developed by the government and the media with the understanding that commanders in the field have final say.

But the task force added, "Just as the president and his civilian deputies bear the responsibility of prosecuting a war, so must they assume responsibility for policy decisions on press access and censorship."

The report recommended that courses be taught at journalism schools and military academies so that reporters and soldiers know more about each other.

"We are asking that each take account of the role of the other in a Democratic society," said Ed Fouhy, executive producer for NBC News and a task force member.

Task force chairman Edward Costikyan said access "is not one of conflict between the military and the media, but rather the political government and the media."

Craig R. Whitney, assistant managing editor of The New York Times, said the report was an attempt "to issue a call" to the government after reporters were excluded from Grenada. "We somehow lost our 200-year tradition of having our military being open to the press," he said, predicting that "Grenada will not be repeated the same way again."