The Emir of Kuwait staged a small bit of theater in his office today. The cast of characters included the American ambassador, Frank Maestrone, four American journalists and Kuwait's minister of health. The principal prop was a pack of Marilboro cigarettes.

There had been no rehearsal the dialogue rambied a bit, since the event was advertised only as a courtesy call. But the lesson was clear - his highness the emir, Sheikh Sobak Salim Sabah, 62, is again in good health and there is no need to speculate about the succession.

He spent most of last winter in London beign treated for a heart ailment. To the distress of the ruling family, reports that the emir was seriously ill circulated throughout the Middle East. The British newspaper Financial Times has been banned for reporting that there was a power struggle within the family to determine who would be named heir apparent when the present crown prince ascended to the throne.

The emir rarely receives foreign journalists, and the Americans had made no request to see him. The Ministry of Information arranged the visit and invited Maestrone, giving the impression that the emir had something to say.

When the visitors were shown into the emir's large, sunny office, decorated in wood paneling and gold-on-ivory wallpaper, he rose quickly to greet them with firm handshakes. He had a cold and looked considerably thinner than in his photograph, but could not be described as frail.

Enter the minister of health, Dr. Abdel Rahman Awadi. One of the emir's retainers explained that Dr. Awadi had come to report to the emir on a World Health Organization conference from which he had just returned. The Americans were invited to stay and "see his highness conducting his daily business."

The minister's report on his conference was brief, and the conversation turned to Kuwait's own public health-care program, probably the most lavish in the world.

If, for example, a Kuwaiti woman needs an operation that cannot be performed here, Dr. Awadi said, the government pays for her trip to London and for a companion as well, since it would be improper for her to travel alone.

A polite inquiry after the state of his highness' health seemed to be in order and was duly made.

"He is all right now, really," the minister said. "He had some discomfort but everthing is all right."

Out came the royal cigarettes.

"We tried to stop him from smoking," said the minister with a laugh as the emir lit up. "He won't do it, but it's all right because he puts little holes in the paper so he doesn't get any smoke. He just sucks on them."

This banter on the subject of health gave the emir a change to get in another little message for the Americans.

"Kuwait has a high incidence of diabetes," he said, "because the people don't exercise. They go everywhere in their cars. They should walk more, and ride bicycles." He suggested jokingly that the Arab oil states were acting out of concern for Americans' health in raising the price of oil to cut down driving.

The emir related other aspects of American life to some of his own concerns.

What, he wanted to know, was the reason fro the consumers boycott of meat a few years ago? (Kuwait's butchers are striking for higher prices.) Why are prices on Western-made industrial goods rising so fast? (He bought an American car for about $1,000, in Kuwait, 40 years ago. The same make sells here for today for 10 times as much.)

When his visitors rose to leave, he offered to let them take his picture. He put out his cigarette and hid the pack before the shutters were snapped.

"The minister of health asked me not to smoke in public or on TV," he said. "It undermines his big anti-smoking campaign."