JERUSALEM — The man who ran Israel’s Mossad spy agency until January contends that Israel’s top leaders lack judgment and that the anticipated pressures of international isolation as the Palestinians campaign for statehood could lead to rash decisions — like an airstrike on Iran.

The former intelligence chief, Meir Dagan, who stepped down after eight years in the post, has made several unusual public appearances and statements in recent weeks. He made headlines a few weeks ago when he asserted at a Hebrew University conference that a military attack on Iran would be “a stupid idea.”

This week Mr. Dagan, speaking at Tel Aviv University, said that attacking Iran “would mean regional war, and in that case you would have given Iran the best possible reason to continue the nuclear program.” He added, “The regional challenge that Israel would face would be impossible.”

Mr. Dagan went on to complain that Israel had failed to put forward a peace initiative with the Palestinians and that it had foolishly ignored the Saudi peace initiative promising full diplomatic relations in exchange for a return to the 1967 border lines. He worried that Israel would soon be pushed into a corner.