TEHRAN, Sept. 25 -- Iran is "hopeful" about comprehensive nuclear deal in the short time left, Iran's President Hassan Rouhani said in his address to the UN General Assembly meeting on Thursday, according to Iranian local media report.

Iran is determined to continue its nuclear activities, including uranium enrichment on its soil, Rouhani said, adding that his country will not slacken over its nuclear rights.

The prospect of "a nuclear deal can be the initiation of multilateral cooperation for security, peace and development in the region and in the world" provided that "the West does not miss this historical opportunity," Rouhani said.

Diplomacy is the only proper way to resolve Iran's nuclear standoff, otherwise, it will be "a grave mistake" to resort to other means to tackle the issue, he said.

On Thursday, Iran's senior nuclear negotiator Abbas Araqchi said key issues are the sources of disagreement between Iran and the world powers in the ongoing nuclear talks,

"We have not been able to narrow the gaps over the key issues and we haven't reached a point of agreement over them," Araqchi told IRIB state TV, adding that "of course, both sides are at work to reduce the differences."

The Iranian nuclear negotiator did not refer to major differences between Iran and the P5+1 group, -- Britain, China, France, Russia and the United States plus Germany -- in the talks, but said that some progress has been made in the areas where positions are not so apart.

"What is of importance for us is to insist on our nuclear rights and observe our red lines which would not be transgressed," he said.

Asked about the possibility of promoting the ongoing talks to a higher level, Araqchi said that "No, it is very unlikely, since we have not reached that point yet."

Uranium enrichment capacity of Iran is one of the key issues in the nuclear talks. The West demands Iran dramatically lower its enrichment capacity. Western media reported recently that Iran and the world powers are working on a new proposal by the West based on which Iran would be allowed to have more uranium enrichment centrifuges but will be disconnected from the feeds of uranium.

Iranian officials or nuclear negotiators have not made any public comments on the reported proposal so far.

Iran is determined to reach a final deal with six world powers over its nuclear program and the West should seize this "rare" opportunity to settle the "fabricated" nuclear dispute, Iran's Foreign Minister Mohammad-Javad Zarif also said echoing Iran's president's remarks.

The top Iranian diplomat expressed Tehran's firm determination in considering any proposal aimed at resolving the country's nuclear issue, Press TV reported on Thursday.

Iran and six countries started a new round of talks over Iran's nuclear program Friday at the UN headquarters. The talks are expected to last a week.

In July, Iran and the six countries agreed to extend negotiations over Iran's controversial nuclear program for another four months till Nov. 24 as they could not narrow down the significant gaps on core issues during the past six months.

An interim deal, which took effect on Jan. 20, was designed to buy time for negotiations. Under the deal, Iran would suspend some sensitive nuclear activities in exchange for a limited sanction relief.