A nation whose public image includes the sinister profile of Count Dracula and the trim, athletic figure of Nadia Comaneci gave a luncheon reception yesterday to celebrate 100 years of American-Romanian diplomatic relations.

The chief activity at the party was tightrope-walking, but Romanian diplomats are so used to doing this that nobody even seemed to notice.

Besides succulent buffest of American and Romanian food, the luncheon featured some fine specimens of the art of diplomatic oratory: the art of saying more than you say -- or perhaps of seeming to say more than you are saying.

"The establishment of diplomatic relations in 1880 marked an important moment in the history of relations between our two countries," said Romanian Deputy Foreign Minister Maria Groza, to the surprise of nobody present.

"We have had our ups and downs," she added. One of the ups (unmentioned at the reception) was World War I, when Romania fought on the side of the Allies. One of the downs (also unmentioned) was World War II, when Romania was taken over by a Fascist dictatorship and its army marched into Russia like meat into a meatgrinder. Since the mid-'60s, while remaining closely tied to its big neighbor, the U.S.S.R., it has tried to maintain an independent foreign policy. This was easier when the slogan was detente and it has been very difficult since the invasion of Afghanistan.

At the moment, Groza said, we are in "a complicated phase of international life, marked by a deterioration of relations," and there is "no more important or urgent task than to take steps to reverse this trend."

These efforts should be based on "respect for national independence and sovereignty and the right of nations to decide their own fate without outside military interference," she said, and then she raised a toast to President Carter, "the prospertiy and happiness of the American people, and the deepening friendship of our two countries."

Undersecretary David Newson, representing the Department of State, said he certainly agreed with her sentiments on "territorial integrity, sovereignty and noninterference in internal affairs." Were they talking about Afghanistan, he was asked, and he laughed. "We were talking about Afghanistan earlier," he said.

Guests at the reception included various members of the diplomatic corps, State Department types and businessmen -- all fairly predictable. More surprising -- in fact, almost unheard-of at an Eastern European embassy party -- were officials of the Anti-Defamation League and the American Jewish Committee. The reason, explained Hyman Bookbinder of the AJC, was Romania's unusually open attitude toward Jews and Israel, with which it has diplomatic relations. "The American Jewish community has always had positive feelings toward Romania," he said. "It is more cooperative than other Eastern European countries, for example, in allowing Jews to emigrate, and we are here to show our appreciation."

The businessmen at the reception also seemed to have an unusually positive attitude. "They're probably the most proficient producers in Eastern Europe," said H. K. Baboyian of UOP, Inc., which has been supplying equipment and technology to the Romanian petroleum industry for more than 40 years, through a variety of political changes. "We have found them to be good trading partners and have had no substantial problems."

When Romania opened diplomatic relations with the U.S. in 1880, it was just beginning to be an independent nation after serving for centuries as a ping-pong ball between the Ottoman, Russian and Austro-Hungarian empires. It was a crossroads between Europe, Russia and the Middle East, and in the time-honored style of crossroads, it was frequently trampled. Before becoming a Socialist republic, it was an exploited province, a feudal fief, a constitutional monarchy, a dictatorship and fairly often a scene of anarchy and revolution. During part of the time it was a subject of the Ottoman Empire, the right to rule in Romania for seven-year periods used to be auctioned off to the highest bidder by the sultan in Constantinople. Today, when Romanian diplomats talk of their country's yearning for peace, one is inclined to believe them.

After chatting with Groza for a few minutes about her visit to Capitol Hill yesterday and her appointment with Secretary of State Muskie today, Newsom thanked her for "seeing to it that I had lunch" and excused himself. "I have to go off to celebrate the 1,400th anniversary of Islam," he explained.