Appealing for an end to Iranian "terrorism," the wives and mothers of four American hostages announced yesterday that they will go to Europe next week to press for increased allied support to gain the captives' release.

"Diplomacy and international law are also being held hostage," Louisa Kennedy, whose husband is a hostage, said at a news conference here. "We ask for a people-to-people bond. Our appeal is not just to the heads of state, but to the families of Europe -- families like us, who, we pray, will never have to bear the pain of what we feel daily."

The news conference was held before reports circulated quoting Ayatollah Ruhollah Khomeini as saying the hostages will not be freed until the American elections are over next November.

The hostages' relatives said they would leave Tuesday evening for Britain, France, West Germany, Italy and Luxembourg. Their one-week trip will coincide with meetings in Luxembourg of leaders of the nine European Common Market nations, at which stiffer sanctions against Iran are expected to be considered.

The families' announcement followed by one day President Carter's warning of possible military action against Iran if stepped-up economic and diplomatic pressures by the United States and its allies fail to secure the hostages' release.

The hostages' relatives sought to draw a clear distinction between their European trip and official U.S. moves. "We are not an arm of the State Department," said Kennedy, who is also the news media representative of FLAG (Family Liaison Action Group), a recently formed organization of hostages' families.

Kennedy, whose 49-year-old husband, Moorhead, was economic and commercial officer for the embassy in Tehran, has been in the forefront of efforts by the families to maintain public support for U.S. moves to free the hostages. The three other hostages' relatives planning to go to Europe have appeared in a public forum only rarely.

They are Gisela Ahern, wife of political officer Thomas L. Ahern Jr., 48, who was denounced by Iranian militants in December as a spy; Pearl Golacinski, mother of security officer Alan Bruce Golacinski, 29, and Jeanne Queen, mother of fice consul Richard I. Queen, 28.

All four speak foreign languages, and some of the women gave interviews for European news media in German, Spanish and other languages after yesterday's news conference at the State Department.

In another development, Kennedy confirmed that all 50 hostages believed to be held at the embassy compound in Tehran were seen Monday by representatives of the International Committee of the Red Cross. Every hostage's family "had a phone call from a Red Cross official early this week" notifying them of the visit, she said.

The International Red Cross had reported interviewing all the hostages, but refused to say how many were in the compound. In addition to the 50 captives there, three Americans are confined at the Iranian foreign ministry. c

Asked about the captives' health, Kennedy said: "The hostages at this time, judging by letters (received by their families), seem to bear up very well considering their circumstances."

Meanwhile, White House and State Department spokesmen said yesterday that U.S. officials are exploring, through diplomatic channels, the possibility of arranging visits to Tehran by hostages' families. The disclosure was prompted chiefly by controversy surrounding efforts by Barbara Timm to go to Tehran to see her hostage son, Marine Sgt. Kevin J. Hermening, 20.

The prospect of such visits drew a cautious response from Louisa Kennedy, who expressed concern that trips to Tehran by hostages' families might result in Iranian propaganda and delay the captives' release. "The more propaganda that Iran can derive from this situation, the longer they are likely to keep it up," she said.

On their trip to Europe, Kennedy said, the relatives will seek to talk with high-ranking officials and with citizens of the five nations. They do not plan to visit other countries, she said. Despite FLAG's asserted independence, Kennedy expressed general support for the Carter administration in its efforts to secure the hostages' release.

"We continue to support the administration because we do believe that they are trying to achieve a safe and speedy release of the hostages," she said. "To the people of Europe we say, "Please consider yourselves important in influencing the Iranians and do not underestimate the impact of your actions.'"