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Obama said in a news release that the deal "will advance our goal of preventing Iran from obtaining a nuclear weapon."
"I have no illusions about how hard it will be to achieve this objective, but for the sake of our national security and the peace and security of the world, now is the time to give diplomacy a chance to succeed," he said.
E.U. negotiator Catherine Ashton also praised the deal, saying that "the foundations for a coherent, robust and smooth implementation ... have been laid." German Foreign Minister Frank-Walter Steinmeier called the deal "a decisive step forward which we can build on."
Meanwhile, U.S. Secretary of State John Kerry said that further negotiations "represent the best chance we have to resolve this critical national-security issue peacefully and durably."
The deal still faces potential roadblocks, however.
Among them is a measure proposed by U.S. lawmakers to blacklist several Iranian industrial sectors and to bar banks and companies around the world from the U.S. market if they help Iran export any more oil. The provisions would take effect only if Tehran violated the interim nuclear deal or lets it expire without a follow-up accord.
This has caused anxiety in Iran, where hard-liners have called the deal a poison chalice and are threatening legislation to increase uranium enrichment. Araghchi has said any new sanctions would halt the deal.
In his news release, Obama said that "unprecedented sanctions and tough diplomacy helped to bring Iran to the negotiating table." But he cautioned against implementing more.
"Imposing additional sanctions now will only risk derailing our efforts to resolve this issue peacefully, and I will veto any legislation enacting new sanctions during the negotiation," he said.
Al Jazeera and wire services