"Because I'm on foreign soil, I don't want to be creating new foreign policy for my country or in any way to distance myself from the foreign policy of our nation, but we respect the right of a nation to defend itself," the former Massachusetts governor told CBS' "Face the Nation" a few hours before the speech and a day before a major fundraiser in the city.
Obama has affirmed the right of Israel to defend itself, while also warning of the consequences of an Israeli strike on Iran.
"Already, there is too much loose talk of war," Obama told the American Israel Public Affairs Committee in March. "Now is the time to let our increased pressure sink in and to sustain the broad international coalition we have built."
An Obama ally, U.S. Sen. Dick Durbin, reaffirmed Obama's position that the U.S. "will stand with Israel."
"But this president has understood that the two choices between all-out war and Iran having a nuclear weapon are choices we don't want to face," Durbin told CNN's "State of the Union."
"I understand Mitt Romney is on this political tour doing this fundraiser in Israel, but the point is the president has had to sit down as he has over and over again with Prime Minister (Benjamin) Netanyahu and work out a sound policy to avoid the prospect of war."
The Romney adviser, Dan Senor, told reporters earlier in previewing the address that "if Israel has to take action on its own, in order to stop Iran from developing the capability, the governor would respect that decision." He said Romney is careful to note that he believes preventing nuclear "capability," not just a nuclear weapon, is critical.