LONDON (AP) _ The Archbishop of Canterbury has tried to gain the release of four Iranians held in Lebanon in return for Iranian efforts to free British hostages Terry Waite and John McCarthy, the archbishop's office said Wednesday.

Archbishop Robert Runcie ''has persisted in his inquiries but so far to no effect,'' said his spokeswoman, Eve Keatley.

The yearlong effort was disclosed after the Iran Embassy's charge d'affaires in London, Ahkunzadeh Basti, told a news conference there had been little publicity in the West about the Iranians, who have been missing for years and are believed held by the Christian Falange.

Basti suggested the archbishop might have influence with a Christian group.

''We will try to use our influence if we find we have access to the people who may have contact with the kidnappers of the British hostages,'' Basti said. ''But first it is necessary to know what happened to our hostages.''

Mrs. Keatley said Runcie started his efforts after Iran's Parliament speaker, Hashemi Rafsanjani, called attention to an Iranian diplomat, Ahmed Motevasselian, who was abducted in July 1982.

The other three Iranians were not identified by name, but were said to be two other Iranian officials and a photographer.

Rafsanjani said he would do what he could to trace Waite, Runcie's envoy, who has been missing since January 1987. McCarthy, a television journalist, was abducted in February 1986.

No one has claimed responsibility for Waite's disappearance.

In all, 22 foreigners are missing, including eight Americans. The hostage held the longest is Terry Anderson, chief Middle East correspondent of The Associated Press, who was abducted in west Beirut on March 16, 1985.

Mrs. Keatley said there was an exchange of letters between Runcie and Rafsanjani and the archbishop told Basti last May he had extended his inquiries beyond Lebanon.

She said that last September, the archbishop, spiritual head of the Church of England, wrote to Rafsanjani expressing his understanding of the anguish of the families of the missing Iranians, but saying his inquiries had not revealed any information.