Three armed attacks on newsmen in the last three days have convinced Italians that journalists are now the principal target of Italy's most active terrorist group, the Red Brigades.

The latest attack came this morning, when two young terrorists, a man and a woman, shot Emilio Rossi, 54, in the legs. Rossi, the conservative news editor of one of Italy's two state-run television networks, was severly wounded.

Yesterday, in Milan, Indro Montanelli, the editor of Italy's most conservative paper, II Giornale Nuovo, was shot four times in the legs in a similar attack while walking to work.

In Genoa, Vittorio Bruno, 41, the deputy editor of the progressive daily Secolo XIX, got similar treatment Wednesday night for an armed gunman who was waiting for him in the newspaper's garage.

The clandestine Red brigades claimed responsibility in a pamphlet found in Florence that said the actions are part of an attempt "to strike a blow at the men and instruments of psychological warfare."

The Red Brigades operating here since 1970, have frequently resorted to punitive attacks against members of groups they define as "servants of the bourgeois regime."

The first case, in May 1975, involved a young right-wing Christian Democratic politican, Massimo de Carolis, who was put up against a wall and shot in the leg.

After that, the principal targets were industrialists and business executives, migistrates and lawyers. A Genoa prosecutor and his bodyguards were killed by the Red Brigades last year, and the May murder of a top Turin lawyer led to the indefinite postponement of a trial here of several jailed Red Brigade members after jury members declined duty out of fear.

Interior Minister Francesco Cossiga described the shootings as part of "a plan of intimidation against civil liberties and the country's democratic institutions."

He has been asking for greater police powers to combat the new-almost-daily kidnapings described last week by a government spokesman as "the government's major preoccupation."

The spokesman said the government feels that terrorism would subside if it failed to have any effect. But de Carolis, who was shot by the Red Brigades, say terrorism here is likely to escalate. Like many other Italians, he says that terrorism flourishes in Italy because "The state is so weak that violence has been allowed to become an intrinsic part of the political process."

Another major cause of tension, he said is.

Some Italians feel that the Red Brigades' actions are designed to create an emergency climate that will help the Communists; others believe that the moves are calculated to do the opposite by creating an anti-left backlash, and still others think the Bridgades are fanatics convinced that the revolution is at hand.

Bombs found yesterday under newsmen's car in Tuscany and in Florence, and the hijacking tonight of a delivery truck owned by the Milan paper Corriere della Sera, were also thought to be the work of the Red Brigades.