WASHINGTON — With the Iranian president on his way to the United Nations, the confrontation between America and the Islamic Republic is ratcheting up in Iraq and Washington.

American soldiers arrested an Iranian Quds Force operative in northern Iraq yesterday, in a clear signal that the war on Iran’s terror network in the country has not abated. At a press conference in Washington, President Bush emphasized the damage international pressure and mismanagement has done to the Iranian economy as a factor he said he hoped would persuade the mullahs to end their enrichment of uranium.

The diplomatic and military confrontations this week are preview of what is in store at the opening of the U.N. General Assembly on Tuesday. President Ahmadinejad yesterday told CBS News that he was withdrawing his request to visit ground zero and lay a wreath at the site of the terrorist attacks of September 11, 2001. Nonetheless, the Iranian president, who has called for destruction of Israel and whose country hosts senior Al Qaeda leaders, will speak at Columbia University.

The American game plan for next week begins on Friday at Foggy Bottom, where Undersecretary of State Nicholas Burns will host a meeting of senior envoys from the five veto-wielding members of the U.N. Security Council and Germany. The purpose of the parley is to iron out a third resolution condemning Iranian intransigence on the nuclear issue, but privately State Department officials have held out little hope for the meeting.

The track that appears more promising is being pursued primarily by a Treasury undersecretary, Stuart Levey, to entice European and Japanese banks to cut ties with Iranian banks. This summer, the three biggest German banks cut ties voluntarily with Iran, despite the German government’s reluctance to support sweeping sanctions in the U.N. Security Council.

Mr. Bush yesterday contrasted his approach on Iran with that of the French foreign minister, Bernard Kouchner, who earlier this week said that if Iran continued to enrich uranium, there would be war with the West. When asked about the comment, Mr. Bush said: “I have consistently stated that I’m hopeful that we can convince the Iranian regime to give up any ambitions it has in developing a weapons program, and do so peacefully. And that ought to be the objective of any diplomacy. And to this end, we are working with allies and friends to send a consistent message to the Iranians that there is a better way forward for them than isolation, financial isolation, and/or economic sanctions.”

While Mr. Bush focused on economic and diplomatic pressure, American troops in Iraq continued the shooting war against Iran’s terror network. Yesterday, the Pentagon confirmed that American forces in northern Iraq captured a Quds Force operative who had been involved with the smuggling of the copper disc roadside bombs the military calls “explosively formed penetrators.”

“I think it’s a further reflection that they’ve not ceased these activities that we find troublesome and are inconsistent with being a good neighbor to Iraq,” a Pentagon spokesman, Bryan Whitman, said. The operative was the seventh Quds Force member American forces have captured, Mr. Whitman said. Other military officials, however, have told The New York Sun that the overall number of Iranian operatives captured both by American forces and the CIA-created Sunni Iraqi intelligence service is in the hundreds.

A military official who requested anonymity said the arrest signals that earlier reports that Iran had recalled its Quds Force network in Iraq are now likely out of date. “This would suggest the operatives were recalled with the change of leadership of the Revolutionary Guard, but now they are returning,” the official said.

The location of the Quds Force operative’s capture yesterday also points to Iranian collaboration with Sunni terrorists in Iraq. The most prominent Sunni terrorist group in northern Iraq is Ansar al-Sunna, also known as Al Qaeda in Kurdistan. Ansar al-Sunna’s main bases are on the Iranian side of the border with Iraqi Kurdistan.

A former senior Pentagon official under Mr. Bush who is now at the Brookings Institution, Peter Rodman, said that he thought now was the time for America to pursue sanctions with allies and at the United Nations that would deal a “political shock” to Iran. The hope, Mr. Rodman said, is that a ban on foreign investment in the energy sector, for example, would drive the regime to end its enrichment of uranium and nuclear diplomatic escalation.

“It’s a brittle situation. There is evident unpopularity internally with the regime. Something tells me it could work,” he said.

Mr. Rodman said that at the moment he does not favor bombing the known Iranian nuclear reactors. “We have a moral obligation to exhaust all the nonmilitary tools at our disposal by economic pressures before exploring military options,” he said.