JERUSALEM — Israel and the United States have agreed to postpone major joint missile-defense exercises that had been scheduled for the spring because of regional tensions and instability, according to Israel’s foreign minister, Avigdor Lieberman.

The move appears intended to avoid further escalating tensions with Iran, which is under intense international diplomatic and economic pressure to curb its nuclear program out of fears that it is seeking to make a nuclear bomb. Iran itself recently held 10 days of naval exercises near the Strait of Hormuz, and Israel has kept open the possibility of a military strike on Iran’s nuclear facilities.

At the same time, the United States is leading an effort to increase sanctions on Iran, and an Iranian nuclear scientist was assassinated in Tehran, the fourth such attack reported in two years. Iran blames the United States and Israel for the killings.

Speaking Monday on Israel Radio, Mr. Lieberman cited “diplomatic and regional reasons, the tensions and instability” as factors in delaying the exercise. The Israeli military said in a statement that the joint exercise, Austere Challenge 12, would take place during the second half of the year.