Ashkenazi, who is on an official visit to Washington, met Wednesday with US Vice President Richard Cheney and with Deputy Secretary of State John Negroponte.
Major-General Benny Gantz, the military attaché in the United States, hosted a reception for Ashkenzi on Wednesday night, which was attended by senior officials in the American army.
On Thursday, the IDF chief is expected to arrive at the Pentagon for a series of meetings with senior US army officials, headed by Chairman of the Joint Chiefs of Staff Michael Mullen.
"We are all united in thinking that Iran should not be allowed to obtain a nuclear weapon, and there is no doubt that the preference is for diplomatic activity and for sanctions," Ashkenazi said following his meetings Wednesday.
"This is the preferable way, in terms of international activity as well. This is the Israeli preference and the American preference. In addition, everyone understands, both the Americans and certainly us, that we must prepare for all options."
'Very good cooperation with US'
Ashkenazi said the goal of his trip was "to understand the American outlook on the issues and problems in the Middle East. This is an excellent opportunity to make it clear to them how we see things. In this sense we see things eye to eye. We have no disagreements. The cooperation is very good."
One of the visit's main objectives is to expand the cooperation between the IDF and the American army. The chief of staff seemed enthusiastic over what he discovered in Washington.
"The Americans today are fighting wars which are similar to our war on terror. It is often surprising to see how similar these things are. Even the types of explosive devices are very similar to those we deal with in Gaza and opposite Hizbullah."
"It is crucial that we stop the Iranian aggression," Ashkenazi said during his reception, noting that it was rare to see a democratic country facing so many threats.
"We must set priorities, but we cannot ignore any of the many threats," he said. "These are complex threats which entail international intervention."
The IDF chief concluded by saying, "My duty is to ready the army for war, to fight and to win."