Chiefs of mission from more than 60 countries, in the first of two such diplomatic events planned within the next week, had dinner at the White House last night. Before it was over, Poland's charge' d'affaires used the occasion to plead his country's case directly to the president.

"Mr. President," said Zdzislaw Ludwiczak, who arrived here last month after former Polish ambassador Romuald Spasowski asked for and received political asylum, "it is my conviction that what we are doing at home is to settle our differences with our own hands. We will do it."

They stood in the Blue Room where butlers served after-dinner coffee and liquors from silver trays. President Reagan, who had met Ludwiczak and his wife, Zofia, at the beginning of the evening, listened quietly to the Polish diplomat's impassioned presentation, but he offered few comments.

Afterwards, Ludwiczak, who called it "a difficult and complex time for Polish-American relations," said it was "difficult to say" what the president's reaction had been. "I will have to assess that for myself."

A few minutes earlier, Ludwiczak told a reporter that "we are doing what we can to settle our problems by our own measures, and I am very optimistic."

"He's a born optimist," interrupted his wife.

Then excusing themselves, the two of them circled the room where near the fireplace, with logs ablaze, Reagan was the focal point. Soon, Zofia Ludwiczak was standing some distance apart as her husband walked up to the president. His characteristically friendly smile soon changed to a look of sober concentration.

Ludwiczak was not the only diplomat anxious to get the president's ear. Wandering in from the other state rooms, they quickly caught on that by standing in line they had a chance to talk privately with Reagan. Their approval was unanimous.

"It's really a unique experience and very special," said Yugoslavian Ambassador Budimir Loncar. "Everyone -- big or small -- has a chance to feel equal and talk to the president."

For his part, President Reagan seemed surprised that he and the first lady were reviving a tradition of diplomatic dinners that went out with the Nixon administration. The second wave of the corps, which like last night includes envoys to the Organization of American States, will come to dinner next Thursday.

"I didn't know we were starting something over again." He said he liked the chance it offered for give and take "because I've always felt that we ought to talk to each other instead of about each other."

Besides the diplomats, nearly a dozen top administration officials were there acting as table hosts, in- cluding Vice President and Mrs. Bush, Deputy Secretary of State Walter Stoessel Jr. and his wife, Mary Ann, national security adviser William P. Clark and his wife, Joan, Chief of Staff James Baker and his wife, Susan.

Unlike the Reagans' champagne and dessert reception for them last year when white tie was de rigueur, the diplomats were advised to wear black tie. A White House spokeswoman said it was not the Reagans' intention to tone down the grandeur.

"I don't think it was thought of in those terms, but rather that diplomats would be more comfortable in black tie spending a long evening," said Sheila Tate, the first lady's press secretary.

Those who thought they were going to eat off the new Reagan china were in for a disappointment. The problem that had prompted its purchase in the first place was still a problem.

"There's not enough," said Tate of the $209,000 red and gold Lenox service, only half of which arrived last week. The remaining 120 place settings are scheduled to arrive later in the year.

So the 160 guests ate supreme of smoked trout en gele'e, tenderloin of veal in chablis wine and chestnut mousse with caramel sauce from the Johnson china on 16 round tables set up in the East Room. They laughed when President Reagan offered them his toast and then admonished them not to break their glasses in the fireplace.

"Some might say this room is a microcosm of the problems the world faces," he had told them in a more serious vein, "but to me this gathering is a sampling of the oppor- tunities we have to communicate on personal levels and to cooperate as representatives of our independent nations."

The response fell to Egyptian Am- bassador Ashraf Ghorbal, who is sev- enth in the order of diplomatic pre- cedence but moved to the top of the list when the White House notified him that the dean of the corps, So- viet Ambassador Anatoliy Dobrynin was in Moscow, and the others out- ranking him were also out of the country.

"I must admit that I enjoy it, I love it," said Ghorbal. "Our dean had better hurry back before I have wild ideas."

There was no doubt that reviving the dinner for the diplomats had their approval, he said.

"As you know, diplomats are tra- ditionalists. We assure you we will not waver from the beautiful tradi- tion you set tonight. You have our commitment to see you next year, same time."

"Oh, I expect we'll do it again," said the president who, with the first lady, was among the last to leave the party.