WASHINGTON — A majority of Americans would oppose joining Israel in a war should it strike Iran, a poll showed.

The Chicago Council on Public Affairs poll, released Thursday, shows 56 percent of respondents answer “No, it shouldn’t” to the statement, “If Israel were to bomb Iran’s nuclear facilities, Iran were to retaliate against Israel, and the two were to go to war, the United States should or should not bring its military forces into the war on the side of Israel.”

Those responding, “Yes, it should” amounted to 38 percent. In other findings, a majority — 58 percent — favored “making a major effort to resolve the Israeli-Palestinian conflict” as a measure to fight terrorism, with 39 percent opposing.

The Chicago Council’s analysis said support had dropped for including American troops in an international peacekeeping force to maintain an Israeli-Palestinian peace agreement; Americans were now split, 49-49, whereas majorities had in the past supported such participation.

Another finding showed that Americans are statistically split on using U.S. troops to defend Israel if it were attacked — 47 percent in favor, 50 percent opposed.

There was a sharp rise since 2004 in the number of Americans who think the United States should take Israel’s side over the Palestinians — from 17 percent to 28 percent, while 66 percent said it should take no side and 3 percent said it should favor the Palestinians.

Israel scores much higher than the Palestinian Authority on the “warm, favorable feeling” scale, 57 to the P.A’s 32.

Other Middle East ratings were 49 for Turkey, 39 for Saudi Arabia and 27 for Iran. Asked the status of relations, 44 percent said “about the same,” 38 percent said “worsening” and 12 percent said “improving.”

The poll was taken between June 11 and June 22 when tensions between the Obama and Netanyahu administrations were just beginning to abate.

A strong majority — 62 percent — said Israel should not build settlements. Asked to rank nations’ importance to the United States, Israel placed sixth, tied with Saudi Arabia.

The poll was conducted for the Chicago Council by Knowledge Networks. The number of respondents was 2,596, and the poll had a margin of error of 1.9 percentage points.