Secretary of State George P. Shultz said yesterday that the United States will negotiate with the Soviet Union before deploying a space-based antimissile system, but that "this does not mean giving the Soviets a veto over our defensive programs."

Speaking to the Austin Council on Foreign Relations in Austin, Tex., Shultz said the U.S. commitment to negotiate reflects "a recognition that we should seek to move forward in a cooperative manner with the Soviets" on strategic defense, embodied by President Reagan's Strategic Defense Initiative, dubbed "Star Wars."

Special arms adviser Paul H. Nitze, speaking at the International Institute for Strategic Studies in London, used virtually the same words as Shultz in describing the U.S. position on negotiations with the Soviets at the time of a future Star Wars deployment.

An administration official said the wording of the statements was chosen in an effort to set forth the U.S. position about deployment in an authoritative way. The official, who asked not to be identified, could not clear up the apparent contradiction between willingness to negotiate with the Soviets and the statement that the Soviets will not have a veto. The Shultz and Nitze speeches were made public at the State Department.

Most European and Asian allies have expressed willingness to go along with Star Wars research, but there is much less consensus about the plan beyond the research phase.

The 1972 Antiballistic Missile Treaty between the United States and Soviet Union bans deployment of nationwide ABM systems. Both sides agreed in a written statement issued at the time that, in the case of future ABM programs using "other physical principles" such as particle beams or lasers, limitations would be set in an amendment.

If a U.S.-Soviet deadlock develops in negotiations about possible deployment of antimissile systems, the United States would have the option of abrogating the treaty. The pact can be canceled by either party with six month's notice if it decides that "extraordinary events related to the subject matter of this treaty have jeopardized its supreme interests."

It will be years, in any case, before a decision about Star Wars deployment can be made. Nitze said yesterday that the object of the research is "to provide the basis for an informed decision, sometime in the next decade," of the feasibility of a Star Wars defense plan.