Mr. Netanyahu’s political party, Likud Beiteinu, issued a sharp statement condemning Mr. Peres for expressing a “personal political opinion that is disconnected from the Israeli public’s stance,” and the prime minister himself said that “the diplomatic process must be managed responsibly and sagaciously and not in undue haste.”

Mr. Peres weighed in again on both Iran and the peace process in Monday’s radio interview.

Many Israeli analysts see Mr. Obama’s hesitation on attacking Syria, despite his earlier statement that chemical weapons use was a red line that would prompt White House action, as a harbinger that Washington might similarly waver on its vow to prevent Iran from developing a nuclear bomb.

But Mr. Peres said Monday that “Obama will not allow nuclear weapons in Iran,” and that Israel “will not have to be alone in this campaign, because it is a vital American and world interest that threatens the world and not only Israel.”

Further, he said, “Israel can’t do it,” a statement that defies Mr. Netanyahu’s frequent insistence that Israel must and can defend itself by itself from all security threats, including Iran.

Regarding the peace process, Mr. Peres said Mr. Netanyahu “took a difficult decision” in restarting direct negotiations with the Palestinians this summer. He again praised Mr. Abbas as someone “who says he is in favor of peace, who is in favor of a Jewish state.”

Mr. Peres maintains close relationships with many foreign leaders, who generally include a meeting and a photo opportunity with him during their official visits here. He has long been an admirer of Mr. Obama, who awarded him America’s highest civilian honor, the Presidential Medal of Freedom, in June 2012. Mr. Peres returned the gesture by bestowing Israel’s Presidential Medal of Distinction on Mr. Obama during his visit here in March.

“I trust President Obama,” Mr. Peres said in the radio interview on Monday while discussing Syria. “I think it is permissible to weigh matters. It is better to weigh before and not after. I have confidence in him when it comes to Israel.”