Last week's negotiations in Vienna between diplomats from Iran and the G5+1 took place in a good and constructive atmosphere," Chelbi said in her weekly press briefing in Berlin on Monday.
Chelbi, however, said that the differences still remained and had to be sorted out.
She cited German Foreign Minister Frank Walter Steinmeier as saying that while the July 20 target date should not be questioned, the tough issues had still to be addressed and that's why all parties were working intensely to achieve a negotiated solution in the Iran's nuclear standoff with the West.
Representatives of Iran and the G5+1 ended their fifth round of talks on Friday over a final agreement on Tehran's nuclear program.
Before the talks, Iran and the world powers said that they were resolved to start drafting a long-awaited final deal in the fifth round of talks.
But Iranian Foreign Minister Mohammad Javad Zarif told reporters after the latest round of talks with the six world powers that although the seven nations have started compiling the draft deal, the harsh stance taken by the western powers, which is reflected in their excessive and maximum demands show that they are not fully ready to enter serious negotiations to attain a final solution to the decade-old standoff.
He stressed that Iran would not give up its rights, and would continue resistance until restoring all its nuclear rights.
Yet, Zarif said the seven nations are now working on the introduction to the deal.
"We have entered the phase of drafting the agreement, but we can't say we have agreed on a common thing as we have not reached an understanding over essential subjects," Zarif told reporters after four days of talks in Vienna on Friday afternoon.
"The talks were intensive and still continue. The discussions started this morning with my meeting with Mrs Ashton and now Mr Araqchi and Ravanchi and the rest of our team are working on the introduction of the text (of the final deal) with Ashton's deputy," he added.
"The introduction deals with the goals, frameworks and mechanisms and the way differences can be resolved," Zarif said, adding that attaining agreement over the introduction of the text of the final deal is likely.
Zarif said although the seven nations have started drafting the deal, "we can't say that we have a common text as in many items there are different views over the content and the way the agreement should be written".
The Iranian foreign minister complained that "the opposite side has not attended the talks with the needed preparedness to enter serious negotiations on the basis of the realities".
He said Iran has offered solutions to some differences based on the Geneva interim deal, but the opposite side is raising "excessive demands and Iran will not give up the Iranian nation's interests and rights due to these excessive demands".
He said Iran has always held logical stances and demands based on the international laws and solutions which are based on the previous agreements, "and we stand firm on our words".
Zarif reiterated Iran's goodwill, and said Tehran is serious about a deal.
The Iranian lead negotiator said his team has worked hundreds of hours on the text, adding that Tehran and the six powers have so far worked ten hours on the draft jointly.
He said the next round of the talks will start in Vienna on July 2, "and we will continue the negotiations as long as they are useful and needed and until achievement of the results."
He asked the West to be realistic, and reminded that the International Atomic Energy Agency has announced earlier today that Iran has complied with its undertakings, which proved Iran's goodwill.
Zarif complained that during the talks only the maximalist and excessive demands of one of the powers is raised, and asked the 5+1 members to work more among themselves to reach a common stance which would help the negotiations move towards a solution.
"Position-taking would not lead to an agreement, we have come here to attain a solution," Zarif said, adding that Iran has presented a specific definition for its practical needs, and the other side should also think of a solution to the "unnecessary" decade-old crisis and problem instead of chanting slogans which are good only for interviews for domestic consumption and satisfying certain parties.
He once again stressed the need for the removal of all sanctions, and said, "I am still hopeful about (attaining a) solution because I believe the issue is not complex."
The Iranian foreign minister also criticized the world powers for their slow and delayed compliance with their undertakings under the Geneva interim nuclear deal.
