The participation of Tehran, a close ally of Syrian President Bashar al-Assad, has been a sticking point in the long-delayed peace conference.
“As I have said repeatedly, I believe strongly that Iran needs to be part of the solution to the Syrian crisis,” Ban said in New York.
Al-Assad’s regime has been fighting an insurgency that arose after protests were suppressed nearly three years ago.
The Geneva II conference, scheduled to start Wednesday, will bring Syrian officials and the opposition to the negotiating table for the first time since the war began in March 2011.
Ban called the conference in the Swiss town of Montreux a “long-awaited chance to end the violence and begin putting the country back together.”
He welcomed the Syrian National Coalition’s decision Saturday to attend the peace talks.
“Over the past 48 hours, I have had a series of intensive meetings and telephone conversations with many global leaders and others who are part of the diplomacy aimed at helping Syria to regain the path of peace,” he said.
“I have been striving to generate momentum and to create the best possible atmosphere for the success of this crucially important undertaking.”
In addition to Iran, Ban issued invitations to Australia, Bahrain, Belgium, Greece, the Vatican, Luxembourg, Mexico, the Netherlands and South Korea.
“I believe the expanded international presence on that day will be an important and useful show of solidarity,” he said.
Ban said he had “spoken at length in recent days” with Iranian Foreign Minister Mohammad Javad Zarif, who had “assured me that, like all the other countries invited to the opening-day discussions in Montreux, Iran understands that the basis of the talks” is the full implementation of the Geneva Communique of June 30, 2012.
The US and Russia have worked since then to organize the talks.
Russia supported Iranian participation, while the US insisted that Iran, which the West accuses of providing battlefield support to al-Assad’s regime, must first back the aims of the conference.
US State Department spokeswoman Jen Psaki said Washington viewed the invitation “as conditioned on Iran’s explicit and public support for the full implementation of the Geneva communique,” including a transitional governing body with full executive power.
“This is something Iran has never done publicly and something we have long made clear is required,” she said.
“We also remain deeply concerned about Iran’s contributions to the Assad regime’s brutal campaign against its own people, which has contributed to the growth of extremism and instability in the region. If Iran does not fully and publicly accept the Geneva communique, the invitation must be rescinded.”
Ban said that he and Zarif had agreed “that the goal of the negotiations is to establish by mutual consent a transitional governing body with full executive powers” in Syria.
“It was on that basis that Foreign Minister Zarif pledged that Iran would play a positive and constructive role in Montreux,” Ban said.
He called on “all those who come to Montreux to act in good faith,” emphasizing that the direct negotiations between al-Assad’s regime and the Syrian opposition would begin Friday in Geneva.
“In Montreux, we are gathering countries and organizations to show their solidarity with this process and, of course, with the Syrian people, who have suffered so much,” Ban said.
“I especially appeal to the Syrian parties themselves to keep one goal in mind: the end of the suffering of the Syrian people and the beginning of a transition to a new Syria.”