A top Libyan official has denied Reagan administration charges that Libya supports international terrorism but he indicated the United States and Libya might have different interpretations of what the word terrorism means.

Maj. Abdussalam Jalloud, the country's number two official, also denied in an interview yesterday that there are any Libyan troops or "volunteers" in Lebanon, despite claims by Israeli leaders and by Palestinian leader Yasser Arafat today that there are.

Jalloud, who is libyan leader Muammar Quaddafi's right-hand man, said Libya defines terrorism as "any action which is not based on moral values and which is not based on a just struggle." The Palestin Liberation Organization, which President Reagan has described as terrorist, is considered "legitimate" by Libya, Jalloud said, as are nationalist groups such as the South-West African People's Organization in Namibia.

Support of international terrorism has long been an issue between the United States and Libya and was at the heart of a Reagan administration order closing the Libyan Embassy in Washington this month.

Jalloud said that whether an individual considered a terrorist often depends on the circumstances. For example, he said, Robert Mugabe, prime minister of Zimbabwe, was called a "terrorist" in the Western news media when he was leading guerrilla groups fighting for control of what was then Rhodesia.

Libya, he said, backs the idea of an international conference to discuss measures to combat terrorism, so long as the meeting includes discussions on a definition of the word.

He said Libya had used force to free hostages often when hijacked planes landed here. "Our religion, our Arab values and morals, do not allow us to support terrorism," he said.

To emphasize the point, Jalloud picked up a copy of a decree from his desk and read a portion that says Libya pledges to "combat all forms of terrorism and condemns it." He said this included airplane hijackings, assassinations, taking people hostage or "aggression against innocent civilians."

Jalloud said Libya believed the United States engaged in forms of terrorism when it sent aircraft carriers to "frighten people," denied wheat to starving people or used the Central Intelligence Agency to assassinate.

He said his government had nothing to do with the attempted assassination of a Libyan citizen in Colorado last fall, allegedly by a former U.S. Green Beret said by the Federal Bureau of Investigation to have had ties with Libya. He said even the U.S. government investigation into the incident "hasn't proven anything at all."

He said Libya acted against its exiles only when they "actually took action" against the revolution here and were cooperating with the Egyptian Moroccan or Israeli intelligence services.

The shutdown of the embassy, which Jalloud called a "tempermental reaction" of an "ignorant" government, has raised the question of whether there will be a halt in the flow of Libyan oil to the United States. The Reagan administration has recommended that U.S. oil companies operating in Libya recall their personnel.

Jalloud said Libya has already taken the "necessary measures" to keep its oilfields and its $23 billion petroleum industry operating, should the U.S. oil companies decide to remove their 2,000 American employes. The employes are in no danger, Jalloud said.

Libya sends about 40 percent of its the annual crude oil production to the United States, accounting for about 10 percent of the U.S. imports.

Jalloud refused to say what steps Libya has taken to continue production should the U.S. oil technicians leave but he said Libya was prepared to "live without oil" as it had before oil was discovered here.

He gave no indication whether Libya has decided to cut off oil exports to the United States, a move that would be considered, senior Libyan diplomat Ali Houderi said the day he left Washington.

The interview took place in Jalloud's office in the People's Palace, the old residence of dethroned king Idriss in Tripoli, where Jalloud now oversees the system of Revolutionary People's Committees that are responsible for running the economy as well as the government.

Jalloud said it was "absolutely untrue" that Libya had sent any troops to Lebanon in the current crisis there as the Israeli government has alleged. "There are no Libyan soldiers whatsoever in Lebanon or Syria," he said.

Nor, he added, were there any "volunteers." Libya has asked the Arab world to support sending volunteers to Lebanon and the Arab League meeting in Tunis last week approved the idea in principle.

Israeli Prime Minister Menachem Begin said last week that there are "several hundred" Libyan troops fighting alongside Palestinian guerrillas in Lebanon and Israeli officials said yesterday that an antiaircraft missile site bombed by Israeli warplanes was manned by Libyans.

Palestinian leader Yasser Arafat, at a rally in Beirut today, said, according to a Palestinian account quoted by the Associated Press, "I want to tell Begin that there are Libyan missiles and Libyan forces. They have been fighting with us since 1972 in the Arkoub region" -- the southeast portion near the borders of Israel and Syria.

On the issue of neighboring Chad, Jalloud said Libyan troops have "actually begun a gradual withdrawal" and would continue it "the more we feel the Chad government is capable of taking care of security."

Jalloud contradicted reports in the Western press of discord between Quaddafi and the Soviets during the Libyan leader's visit to Moscow in April. "So far as I know there were no disagreements whatsoever," he said.

He said reports that Libya might sign a treaty of friendship and cooperation with the Soviet Union were "sheer speculation." But he did not rule out the possibility that Libya might do this sometime later.