ROME, SEPT. 25 -- Vice President Bush today pressed Italian leaders to support a second U.N. resolution containing sanctions against Iran for refusing to accept a cease-fire in the Persian Gulf war, but the Italians did not make a commitment, U.S. officials said.

Bush, starting a 10-day European tour designed to showcase his foreign policy credentials just before he formally enters the presidential campaign, also delivered a letter to Italian Prime Minister Giovanni Goria from President Reagan. Officials said the letter, and similar ones Bush is carrying to other allied leaders, offers reassurance of the U.S. commitment to the defense of Western Europe as the superpowers move toward a treaty to eliminate medium- and shorter-range nuclear missiles from Western Europe and Asia.

As of Oct. 1, Italy is scheduled to assume chairmanship of the U.N. Security Council, and Bush, in meetings with Goria and other Italian leaders, urged them to accept a second U.N. resolution with an enforcement mechanism.

The first resolution called for a cease-fire in the Iran-Iraq war but left open the issue of enforcement if a cease-fire is not accepted. The United States is urging adoption of a second resolution containing sanctions, possibly such as an arms embargo against Iran, and drafting of the document began this week.

Bush, speaking to reporters, said the "outrageous act of laying mines in international waters" by Iran "could facilitate getting a second resolution" through the Security Council.

He said, "The U.N. is often downgraded, but here I think the United Nations has an opportunity if it can act in concert, if the Security Council can act in concert, to possibly be a catalyst for ending the conflict, or the potential conflict, or these incidents that result in conflict, like this last one in the Persian Gulf."

A senior Bush adviser said the Italian officials did not make a commitment to the vice president to support a second resolution. According to news reports, Italian Foreign Minister Giulio Andreotti, at the United Nations this week, did not close the door to sanctions against Iran if the efforts of U.N. Secretary General Javier Perez de Cuellar "should turn out to be unproductive."

Reagan has rejected a Soviet proposal for creation of a U.N. commission to study the war.

The Bush adviser said the vice president praised Italy for deciding to dispatch eight vessels -- three frigates, three mine sweepers and two support ships -- to the gulf. Earlier this year, at the Venice economic summit, Italian officials had expressed skepticism about the value of expanding the naval presence in the gulf.