"We are all united over the understanding that Iran must not be allowed to acquire a nuclear weapon and that there is no doubt that diplomacy must be given priority," Major General Gabi Ashkenazi said on Israeli public radio.
"But we all realise, both the Americans and us, that all options must be prepared," said the chief of staff, who is on his first visit to Washington since taking office last year.
Ashkenazi has held talks with military top brass as well as Vice President Dick Cheney, and was due to hold talks today with the chairman of the Joint Chiefs of Staff Admiral Michael Mullen.
Israel and the United States suspect that Iran's nuclear drive is aimed at developing an atomic bomb, a claim vehemently denied by Tehran, which says its programme is designed solely for civilian use.
Although the two close allies continue to say diplomatic and economic sanctions could still dissuade Iran from continuing its programme, Israel and the United States have refused to rule out military action.
