Against a backdrop of increased efforts by the Soviet Union to enhance its position in the Persian Gulf oil states, President Abdel Fattah Ismail of Marxist South Yemen began an official visit to Kuwait today to mend his strained relations with the emirate's conservative ruling princes.

Ismail's arrival in Kuwait was seen as a sign that his radical regime has regained the tolerance, if not the friendship, of some other Arab states. This marks a shift from the general condemnation that led to a censure motion last summer by the Arab League.

The Arab League action, which included a boycott, reflected traditional Islamic abhorrence of communism -- Ismail is the only Communist head of an Arab state -- as well as irritation by Saudi Arabia at having a revolutionary Marxist Country on its southern border.

Saudi Arabia views its troublesome neighbor as a constant menace, but Kuwait often asserts its independence of Saudi political influence. The visit of Ismail follows a state visit to Kuwait by President Tito of Yugoslavia, which amounts to fraternization with Communist governments that the Saudis are not prepared for despite recent Soviet overtures designed to get diplomatic relations started.

The Kuwaiti foreign minister, Sheikh Sabah Ahmed, was quoted by news agencies as saying Ismail's visit would "contribute to the promotion and development of bilateral relations." Last July, Kuwait reluctantly supported the Arab League decision to censure South Yemen and suspend it from the league for having engineered the assassination of the president of neighboring North Yemen.

Kuwait acted then under Saudi pressure. Saudi Arabia is supporting North Yemen in a brushfire war with South Yemen and has been sounding the alarm over reports that the Aden government has imported Cubans and East Germans to fly its Soviet-supplied planes and train armed forces and police.

At the time of the Arab League vote, Ismail, a 40-year-old Marxist ideologue, was head of a pariah regime. He had seized power by overthrowing President Salem Rubaya Ali only two days after the assassination of his counterpart in North Yemen, for which Ismail blamed Rubaya Ali. Rubaya Ali, although pro-Soviet, had been working for improved relations with Saudi Arabia and North Yemen and appeared to be working toward stability on the Arabian Peninsula.

By comparison, Ismail was viewed as an extremist, greeted with outright hostility by moderate Arabs and with ill-concealed suspicion even by other hard liners. But his isolation lasted only until November, when an Arab summit conference in Baghdad brought together all Arab states except Egypt in opposition to the Camp David agreements and the boycott was shelved.

The Kuwaitis, who supply crude oil for the Aden refinery, pride themselves on maintaining ties with all Arab states. Thus it is consistent with their policy to receive Ismail, but it is not clear what the real purpose of the visit is.