The Iranian Students' Association in the United States has organized a demonstration outside Harvard Yard at 2 p.m. today, protesting Harvard's apparent decision to give him an honorary degree and make him the Commencement speaker.

Ahmad Shayegan, a graduate at Stevens Institute of Technology in New Jersey, said yesterday that the details had not yet been worked out, but that he hoped students would walk out on Commencement exercises in protest.

Shayegan said he knows of no Iranian student organization-- in Iran or outside--which favors the Shah's regime. Shayegan said that the United States and the Soviet Union are making "another Vietnam" out of Iran by pouring in millions of dollars worth of weapons.

When the Shah arrived in New York Monday, 200 students demonstrated against him outside the Waldorf-Astoria. Shayegan said he did not know how many demonstrators there would be today.

At the demonstration in New York, Iranian students passed out a leaflet saying, "The Iranian people will never accept that the U. S. has or ever had any right to interfere in Iranian internal affairs. By doing so since 1953, the U. S. has already begun a war against Iran." It said that the Shah was brought to power in 1953 "and imposed upon the Iranian people. He has stayed in power only through military oppression."

The Shah is in the United States on a state visit, for the purpose of negotiating a $600 million purchase of weapons from the U. S. The Shah met with President Johnson Tuesday. The 49-year old ruler is reported to be upset with the planned withdrawal of British defenses from the Persian Gulf late in 1971.