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President Obama staunchly forcefully defended the temporary agreement to freeze Iran's disputed nuclear program on Monday, pushing back against skepticism of the accord voiced by members of congress and some American allies.

Obama, without naming names, swiped at those who have questioned the wisdom of engaging with Iran during a fundraising event in San Francisco on Monday.

"Tough talk and bluster may be the easy thing to do politically, but it's not the right thing to do for our security," he said.

Bipartisan skepticism in the Senate about the deal could mean a renewed push for tougher sanctions, which would present a problem for the Obama administration, since the deal signed with Iran and five other nations guarantees no new sanctions for six months.

Israeli Prime Minister Benjamin Netanyahu, one of the fiercest opponents of the six-month deal, called it a "historic mistake" and announced he would be dispatching a top envoy to Washington to try to toughen the final agreement negotiators will soon begin hammering out.

The weekend agreement between Iran and six world powers -- the U.S., Britain, France, Russia, China and Germany --  is to temporarily halt parts of Tehran's disputed nuclear program and allow for more intrusive international monitoring. In exchange, Iran gains some modest relief from stiff economic sanctions and a pledge from Obama that no new penalties will be levied during the six months.

The U.S. and its allies contend Iran is seeking to produce a nuclear bomb -- of particular concern to Israel, which fears an attack -- while Tehran insists it is merely pursuing a peaceful nuclear program for energy and medical purposes.

"When I first ran for president, I said it was time for a new era of American leadership in the world, one that turned the page on a decade of war and began a new era of engagement with the world," he said. "As president and as commander in chief, I've done what I've said."

Later, at a high-dollar fundraiser in Los Angeles, Obama said he will not take any options off the table to ensure Iran does not develop a nuclear weapon.

However, he added, "I've spent too much time at Walter Reed looking at kids 22, 23, 24, 25 years old who've paid the kind of price that very few of us in this room can imagine on behalf of our freedom not to say that I will do every single thing that I can to try to resolve these issues without resorting to military conflict."

Despite Obama's assurances that no new sanctions will be levied on Iran while the interim agreement is in effect, some lawmakers want to push ahead with additional penalties. A new sanctions bill has already passed the House, and if it passes the Senate, Obama could have to wield his veto power in order to keep his promise to Tehran.

Sen. Marco Rubio, R-Fla., was among those calling for the pursuit of additional sanctions now, arguing that the interim deal does little to take Iran off the nuclear course.

"There is now an even more urgent need for Congress to increase sanctions until Iran completely abandons its enrichment and reprocessing capabilities," Rubio said in a statement.

Sens. Bob Menendez, D-N.J., and Mark Kirk, R-Ill., hope to have the bill ready for other lawmakers to consider when the Senate returns Dec. 9 from its two-week recess, according to legislative aides.

The Kirk-Menendez measure would require the administration to certify every 30 days that Iran is adhering to the terms of the six-month interim agreement and that it hasn't been involved in any act of terrorism against the United States.

The senators hope to send the bill to the White House before the end of the year, said the aides, who spoke on condition of anonymity because they weren't authorized to speak by name on the matter.

Sen. John McCain, R-Ariz., said Sunday that he'll continue to work with colleagues "to keep the pressure on the Iranian regime, including by action on additional sanctions."

“I am concerned this agreement could be a dangerous step that degrades our pressure on the Iranian regime without demonstrable actions on Iran's part to end its pursuit of a nuclear weapons capability – a situation that would be reminiscent of our experience over two decades with North Korea," McCain said in a statement.

Even some members of Obama's own party say they're wary of the deal struck in Geneva.

"I am disappointed by the terms of the agreement between Iran and the P5+1 nations because it does not seem proportional," said Sen. Chuck Schumer, D-N.Y., a close ally of the White House. "Iran simply freezes its nuclear capabilities while we reduce the sanctions."

The Senate's Democratic majority leader, Harry Reid, was noncommittal on the subject of sanctions on Monday. On NPR's Diane Rehm Show, he said that when lawmakers return from their Thanksgiving break, "we will take a look at this to see if we need stronger sanctions ... and if we need work on this, if we need stronger sanctions I am sure we will do that."

The Associated Press contributed to this report.