Here are a couple opportunities to speak on the question of attacking Iran. The Friends Committee on National Legislation offers the opportunity to contact Congress on H.R. 362. This bill asks the president to impose a land, sea, and air interdiction of all people and goods moving into and out of Iran. By whatever name it is called, unless authorized by the UN, this action would be widely construed as a blockade and an act of war by Iran and most of the international community.
An online petition reminds Senator Obama of his comments suggesting that an Obama administration would act on the understanding that genuine security requires a willingness to talk without preconditions (something Iran has offered several times to no avail), and that threats and military action are counterproductive.
The petition also urges Senator Obama to speak out against any acts of war, or acts that might be construed as an act of war, now.