WASHINGTON — The Anti-Defamation League expressed “deep concern” Sunday about “flaws” in the nuclear agreement with Iran that was announced 12 hours earlier, but indicated that it would lobby hard to make sure that a final agreement would “ensure Iran is incapable of building a nuclear weapon.”

ADL National Chairman Barry Curtiss-Lusher and National Director Abraham H. Foxman released a joint statement in which they acknowledged that the efforts to bring Iran to the negotiations table are “an important step forward,” but said that the interim agreement provided Iran with concessions that Iran “has not earned” and warned that in the past, Iran has “used respites from international pressure to surreptitiously make progress in its nuclear program.”

The organization’s leaders emphasized that the main concern is for the US and the international community to maintain pressure on Iran during the interim period while negotiations for a permanent resolution are underway.

Still, ADL leaders were more positive than some of the deal’s harshest critics, emphasizing that the organization “commends Congress and the Obama administration who, together, have built an international coalition and a sanctions regime that we hope will, at the end of the day, halt Iran’s nuclear program.”

The century-old American-Jewish organization stressed that it is particularly concerned by the rift between Israel and the United States that has been increasingly visible in recent weeks. “We understand that, for Israel, this is an existential issue and that America’s stakes in a positive outcome are extremely high as well, but not as critical,” wrote Foxman and Curtiss-Lusher. “Now is the time for both governments to work together more closely than ever toward a solution that will meet their shared goals.”

The ADL was one of the first large Jewish groups to respond publicly to the deal. It was the only one of the four major Jewish organizations who were invited to the White House last month to discuss Iran sanctions to release a response. AIPAC, one of the most vocal organizations on Israel policy in Washington, was notably silent as more and more groups responded to the terms of the agreement, and attempted to shape their lobbying focus in the coming weeks.

The ADL’s response differed from most other Jewish organizations’ responses in its ambivalence — or, at least, its ambiguity in its perspective on the interim talks.

Noah Pollak, executive director of the right-leaning Emergency Committee for Israel, described the deal as “a defeat for the United States and the West,” complaining that “it fails to uphold even the minimum demand of repeated UN Security Council resolutions that Iran must stop enriching uranium.” Pollak, in his statement, called on Congress to “make clear that it does not support this deal.”

“Congress should make clear the United States will support Israel if Israel decides she must act to prevent a regime dedicated to her destruction from acquiring the means to do so,” Pollak added.

Across the political spectrum, J Street quickly welcomed the announcement, arguing in a statement that “the accord has several very important provisions that will effectively freeze Iran’s program and begin to roll it back.”

“Secretary of State John Kerry, Under Secretary of State Wendy Sherman and their negotiating partners deserve our thanks for their clear-eyed pursuit of a diplomatic resolution, which remains the most desirable way to achieve the shared goal of the US, Israel and all parties with a stake in the security and stability of the Middle East,” the organization continued.

In direct contradistinction to Pollak’s announcement, J Street urged Congress “to get behind this agreement and continue to give our negotiators the time and space they need to complete a comprehensive and verifiable agreement with Iran that will lift the nuclear threat from the region and the world.” The organization also reinforced in its statement its support for the administration’s request to Congress to hold off on more, tougher sanctions legislation that will come to the Senate in the second week of December.

Americans for Peace Now was equally enthusiastic about the agreement. APN President and CEO Debra DeLee responded in a statement that “anyone who cares about US national security, the security of Israel, and stability in the Middle East should likewise welcome this agreement.”

APN noted that as a final deal is being negotiated, the sides must consider “serious and very legitimate Israeli concerns about a potentially nuclear-armed Iran.”

The organization called on the Obama administration to “make clear” to the Israeli public that the administration’s negotiating strategy “takes into consideration Israel’s national security interests,” but at the same time urged the Netanyahu administration “to shift gears, cease public attacks on the negotiations and the agreement, and give diplomacy a chance.”

Like J Street, APN also encouraged senators to hold off on new sanctions legislation or any other bills that would constrain the administration’s ability to negotiate freely.