JERUSALEM — Shimon Peres, Israel’s president and elder statesman, spoke out Thursday against the prospect of a lone Israeli military strike on Iran’s nuclear facilities, a message that contradicts the hawkish, go-it-alone line emanating from the offices of Israel’s prime minister and defense minister.

The president’s comments came amid a wave of speculation in Israel and abroad that Prime Minister Benjamin Netanyahu and his defense minister, Ehud Barak, might be weighing the option of a unilateral strike even before the American presidential elections in November, while Israel’s limited military capabilities might still have an impact.

“Now, it is clear to us that we cannot do it alone,” Mr. Peres told Israel’s Channel 2 television in an interview marking his 89th birthday. “We can delay,” he said, referring to the partial damage that Israel’s military could do to the Iranian nuclear program, adding: “It is clear to us that we have to proceed together with America. There are questions about coordination and timing, but as serious as the danger is, this time at least we are not alone.”

Mr. Peres was careful to avoid personal criticism of the political leadership, and the prime minister’s office did not issue any official response. But the Israeli news media widely quoted a sharp retort attributed to “people close to the prime minister,” accusing Mr. Peres of forgetting his place and overstepping his role as president, and castigating him for serious mistakes they said he had made in the security realm in the past.