The Iranian government appears to be steadily leveraging the Islamic State crisis by dangling the possibility of cooperation against the terror group in exchange for a favorable deal on its nuclear program -- despite the Obama administration's insistence that the issues are not linked. 

So far in the latest round of talks, the U.S. is reported to be giving some ground, floating a new proposal that would allow Tehran to keep about half its centrifuges. 

Iranian President Hassan Rouhani, in New York this week for the U.N. General Assembly, said Friday that his country is seeking a "win-win deal." Without addressing the particulars of talks, he made clear Iran ultimately is seeking the elimination of all sanctions and the preservation of the country's "right" to enrich uranium. 

How the Islamic State factors into these delicate discussions remains unclear. 

The White House and State Department said earlier this week the issues are unrelated. 

"The United States will not be in a position of trading aspects of Iran's nuclear program to secure commitments to take on ISIL," White House Press Secretary Josh Earnest said, using an alternate acronym for the Islamic State. 

But reports first surfaced last weekend that Iranian negotiators wanted to see more flexibility on the nuclear issue, in exchange for working with the U.S. and its allies to tackle the Islamic State threat. 

An unnamed Iranian official later pushed back on the claim

But Rouhani, in his U.N. address on Thursday, made clear Iran's cooperation in addressing terror threats hinges on the outcome of ongoing nuclear talks - as he once again urged other nations to drop what he described as "excessive demands." 

Rouhani said a deal could mark the "beginning of multilateral cooperation" and allow for "greater focus on some very important regional issues such as combating violence and extremism." 

In a press conference on Friday, when asked about a possible trade-off, Rouhani said that a nuclear deal could lead to "trust-building" and "cooperation" between the U.S. and Iran. 

Whether Iran's cooperation in addressing Middle East unrest will serve as an effective bargaining chip remains to be seen. 

The U.S. publicly has said it will not cooperate militarily or share intelligence with Iran to address the Islamic State threat. 

Yet Secretary of State John Kerry said this week he was "open to have a conversation at some point in time if there's a way to find something constructive." And the U.S. reportedly notified Iran in advance of plans to strike inside Syria. U.S. military leaders repeatedly have said they want regional partners to help combat the Islamic State on the ground, though for now they're talking mostly about Iraqi security forces and, eventually, Syrian rebels. 

In his address to world leaders late Wednesday, British Prime Minister David Cameron also said Iran could help in defeating the terror group's threat. Cameron spoke hours after meeting in person with Rouhani, the first meeting between the British and Iranian leaders since the Iranian revolution in 1979. 

Former Republican Rep. Allen West advised that the U.S. should not lift sanctions against Iran -- and also should keep Iran out of the ISIS fight. 

"What we need to do is isolate Iran from this situation whole-heartedly," he told "We've got to go back in and try to push Iran out. We have to de-legitimize them as a viable player in this conflagration against ISIS." 

Rouhani, meanwhile, has been openly skeptical of the U.S.-led airstrike campaign against the Islamic State, while calling for terrorism to be confronted. 

On Friday, he questioned what the "end-game" was regarding airstrikes in Syria and claimed they were mostly for show. 

Amid the ISIS debate, the Associated Press reported on details of a modified nuclear plan being offered by the U.S. 

The U.S. ideally wants no more than 1,500 centrifuges left operating, while Iran - which says it wants to use the technology only for peaceful purposes -- insists it be allowed to run at least the present 9,400 machines. 

The tentative new U.S. offer attempts to meet the Iranians close to halfway on numbers, diplomats told The Associated Press. They said it envisages letting Iran keep up to 4,500 centrifuges but would reduce the stock of uranium gas fed into the machines to the point where it would take more than a year of enriching to create enough material for a nuclear warhead. 

Negotiators are running up against a Nov. 24 deadline to reach a comprehensive agreement. 

The Associated Press contributed to this report.