Members of the G5+1 are expecting Tehran's response to their proposals presented during the Almaty talks, Grant said, calling for continuation of talks between Tehran and G5+1.
He reiterated that the sextet took part in the Kazakhstan negotiations, on February 26-27, to follow up negotiations and diplomatic solutions to Iran's nuclear issue.
He further termed the G5+1 proposal as "very serious".
The last round of the fresh talks between Tehran and the Group 5+1 ended in Almaty, Kazakhstan, on Wednesday.
During the talks Iran and the world powers agreed to hold an experts meeting in Istanbul, Turkey, on March 17-18 and then continue their talks at the level of their top negotiators in Almaty, Kazakhstan, on April 5-6.
Before Almaty talks, Iran and the G5+1 have already held three rounds of negotiations in Geneva, two rounds in Istanbul, one round in Baghdad and one round in Moscow. The last round of talks between Iran and the Group 5+1 was held in Moscow in June.
Washington and its Western allies accuse Iran of trying to develop nuclear weapons under the cover of a civilian nuclear program, while they have never presented any corroborative evidence to substantiate their allegations. Iran denies the charges and insists that its nuclear program is for peaceful purposes only.
Tehran stresses that the country has always pursued a civilian path to provide power to the growing number of Iranian population, whose fossil fuel would eventually run dry.
Despite the rules enshrined in the Non-Proliferation Treaty (NPT) entitling every member state, including Iran, to the right of uranium enrichment, Tehran is now under four rounds of UN Security Council sanctions and the western embargos for turning down West's calls to give up its right of uranium enrichment.
Tehran has dismissed West's demands as politically tainted and illogical, stressing that sanctions and pressures merely consolidate Iranians' national resolve to continue the path.
Tehran has repeatedly said that it considers its nuclear case closed as it has come clean of International Atomic Energy Agency (IAEA)'s questions and suspicions about its past nuclear activities.
