Iranian Foreign Minister Mohammed Javad Zarif told world leaders in Germany on Sunday that the time to reach a nuclear deal with Iran is now.

"We are prepared to reassure the international community. This is the opportunity to do it, and we need to seize this opportunity," he told a gathering of the world's top diplomats, reported The Associated Press. "It may not be repeated."

Progress has been made in the past few months of negotiations and it would be unproductive to extend the talks once more, Zarif suggested to the conference following a 90-minute morning meeting with U.S. Secretary of State John Kerry.

"I do not believe another extension is in the interest of anybody," he said. "We're reaching the point where it is quite possible to make an agreement ... and I do not believe anything will be different a year down the road."

The U.S. and its five negotiating partners - the U.K., Germany, France, China and Russia - have been working for 12 years to reach a deal that sets long-term limits on Iran's enrichment of uranium and pursuit of other material that could be used in nuclear weapons.

World powers are concerned that Iran is working to develop a nuclear weapon, but Tehran maintains its nuclear program is only for energy production and medical research purposes, according to the AP.

Negotiations were extended past the Nov. 24 deadline after a failed attempt to reach an agreement on providing sanction relief. A final deadline has been set for June 30, with a deadline set to agree on main points by late March.

If an agreement is reached, Zarif said that all sanctions against his country should be lifted, as they have already failed to stop Iran's nuclear developments.

Iran had 200 centrifuges before sanctions were imposed, and "now we have 20,000," he said, adding, "Sanctions are a liability, you need to get rid of them if you want a solution."

President Barack Obama said on Monday that unless Iran agrees to a basic framework, further deadline extensions would not be useful, the AP reported.

"At this juncture I don't see a further extension being useful if they have not agreed to basic formulation and the bottom-line that the world requires," Obama said at the White House following a meeting with German Chancellor Angela Merkel.

"We now know enough that the issues are no longer technical," he added. "The issues now are: does Iran have the political will and the desire to get a deal done?"