WASHINGTON — President Obama struck back at Prime Minister Benjamin Netanyahu of Israel in a speech to a pro-Israel lobbying group on Sunday, defending his stance that talks over a Palestinian state should be focused on Israel’s pre-1967 borders, along with negotiated land swaps, and challenging Israel to “make the hard choices” necessary to bring about a stable peace.

Mr. Obama, speaking before a conference of the influential American Israel Public Affairs Committee, offered familiar assurances that the United States’ commitment to Israel’s long-term security was “ironclad.” But citing the rising political upheaval near Israel’s borders, he presented his peace plan as the best chance Israel has to avoid growing isolation.

“We cannot afford to wait another decade, or another two decades, or another three decades, to achieve peace,” Mr. Obama said. The world, he said, “is moving too fast.”

Administration officials said it would be up to Mr. Obama, during an economic summit in Paris next weekend, to try to talk his European counterparts out of endorsing Palestinian statehood in a coming United Nations vote, a prospect that would deeply embarrass Israel. Some French officials have already indicated that they are leaning toward such an endorsement.