Former CBS News president Fred W. Friendly, in a scorching criticism of how the networks covered the TWA hostage crisis last month, said yesterday that the news media need to "get it across that terrorists can't shoot their way onto our air."

Now a professor emeritus at Columbia University's school of journalism, Friendly told the House Foreign Affairs subcommittee on Europe and the Middle East that "terrorism is the new war, a species of guerrilla warfare whose battlefield is the television screen and the front page."

Saying that the networks failed to provide "context" and that the competitive frenzy among the networks harkened to the days of yellow journalism, Friendly told the crowded committee room: "I think that the message you have to get across is that the word 'exclusive' is a dirty word."

In what may be the first of many sessions analyzing and second-guessing the coverage of the 17-day hijacking crisis, four network executives vigorously defended their broadcasts against criticism that they allowed the terrorists to exploit the television medium.

NBC News President Lawrence K. Grossman, citing new guidelines for how NBC will publicize its coverage in the future, said that he had reviewed all of his network's videotape on the crisis and found "virtually nothing that I would want to take back or do differently."

Jack Smith, a CBS vice president and Washington bureau chief, said that "we believe that our coverage of the hijacking and captivity of the American hostages was responsible, objective and dependable."

"And we believe that this was true not only of CBS News but of the other major American news organizations as well, both broadcast and print," Smith said.

Robert Siegenthaler, ABC's vice president for news practices, defended his network for getting the story "fast, first and most important, accurately," but he said that the network's coverage had resulted in one change as a result of criticism.

He said that ABC News guidelines will now apply to the program "Good Morning America," previously part of the entertainment division. The change came after ABC's David Hartman asked Amal leader Nabih Berri if he had any words for President Reagan -- in effect, inviting Berri to negotiate directly over the airwaves.

Ed Turner, executive vice president of Cable News Network Inc., told the subcommittee: "In the story which brings us here today, one must inquire: 'Who was injured?' The hostages? No, not because of the cameras. The one tragedy happened away from the media." He referred to the killing of Navy diver Robert Dean Stethem by the original hijackers.

At the hearing, chaired by Rep. Edward F. Feighan (D-Ohio), several subcommittee members made it clear that they had no plans for legislation but wanted the press to examine its flaws and come up with guidelines and solutions.

"At the very least the public media has an obligation to be reflective in a series of public forums like this one," Feighan said.

However, several hostages' relatives said that while on occasion the press intruded on their privacy, generally they were glad for the help in keeping the issue before the public.

Peggy Say -- sister of Terry A. Anderson, one of the seven Americans still missing from Beirut -- said that she refused the State Department's orders to leave her brother's plight to "quiet diplomacy" because she believed the opposite tactic helped bring the 39 TWA Flight 847 hostages home and would help bring her brother back alive.

Say added: "Nobody holds our hand but the media; they are at least interested, sporadically."

Network executives as well as other journalists have been particularly concerned about comments like one Friendly made earlier in the hearing that "I have decided in my 70th year that I am a citizen first and a journalist second."

Most news organizations withheld information about the military people among those in captivity and did not disclose that one hostage had a national security clearance, believing their lives were at stake.