A Ronald Reagan press conference today became a platform for an Italian journalist who denounced the American press for printing an ethnic joke told by Reagan and said afterward that "intelligent Italians" enjoy jokes that make fun of their nationality.

Ugo V. Chirato, representing the American chapter of the World Federation of Italian Press, interrupted a Reagan press conference and asked if he could read a statement. Joe Holmes, Reagan's latest press secretary, tried to stop him but Reagan intervened and allowed Chirato to continue.

Chirato then read a short statement declaring that reporters had violated their "honor code" by printing an off-the-record ethnic joke that Reagan told on his campaign bus during the New Hampshire primary. He also criticized the League of Women Voters for permitting Reagan to be questioned about the joke at a Manchester, N.H., debate among the Republican presidential candidates.

"After careful review of Gov. Reagan('s) political record and his warm relationship with the Italian community, we feel that he never intended to insult or demean any ethnic minority," Chirato said. "Therefore, we assure Hon. Reagan of our human appreciation and friendship, and express the wish of seeing a 'clean' presidential campaign in line with the best tradition of American democracy."

Reagan shook Chirato's hand and thanked him, then left for a rally in Fort Myers while Chirato became the center of his own press conference. He told reporters that Italians were "national victims" of ethnic jokes and liked telling them about each other.

Chirato said the statement he read was agreed to by the 13 members of the American chapter of the Italian press group during a recent meeting in Caracas.

The joke which Reagan told went this way:

"How do you tell the Pole at a cock fight? He's the one with the duck.

"How do you tell the Italian? He's the one who bets on the duck.

"How do you know the Mafia's there? The duck wins."

The press conference broke up amid shouts from reporters of "What about the Pole?" And "What about the ducks?"

Chirato, who wore credentials identifying him as a reporter for the Florida Bulletin, said he was an Italian citizen who reported for a number of Italian-language papers and was based in Miami. He described the joke as "a so-so joke" but said it was not in any way offensive.