The United States is hopeful that all parties can now focus on ending the Syria conflict, State Department said on Monday, after UN withdrew the invitation to Iran to attend an upcoming peace conference in Switzerland.

"We are hopeful that, in wake of today's announcement, all parties can now return to focus on the task at hand, which is bringing an end to the suffering of the Syrian people and beginning a process toward a long overdue political transition," State Department spokeswoman Jen Psaki said in a statement.

The spokeswoman reiterated U.S. stance that the purpose of the conference is the full implementation of the Geneva Communique, including the establishment by mutual consent of a transitional governing body with full executive authorities.

UN Secretary-General Ban Ki-moon had rescinded his invitation to Tehran to participate in the Syrian peace conference slated on Wednesdays, his spokesman Martin Nesirky told reporters on Monday afternoon.

"The secretary-general is deeply disappointed by Iranian public statements today that are not at all consistent with that stated commitment," Nesirky said. "He continues to urge Iran to join the global consensus behind the Geneva Communique. Given that it has chosen to remain outside that basic understanding, he has decided that the one-day Montreux gathering will proceed without Iran's participation."

On Sunday, Ban said he had invited Iran, a main regional ally of the Syrian government, to attend the peace conference known as Geneva II.

The U.S. responded skeptically to the decision, saying the invitation should be rescinded unless Tehran "fully and publicly" accepts the Geneva Communique signed in June 2012.