Mottaki made the offer to meet with the "P5+1" group through Turkey, which might host the negotiations, the government's Islamic Republic News Agency reported.
The P5+1 is the five permanent members of the Security Council -- the United States, Britain, France, China and Russia -– plus Germany.
U.S. Sen. Lindsey Graham, R-S.C., said Saturday the United States should consider "neutering" Iran's armed forces if it does not stop its nuclear program, CNN reported.
Speaking at the Halifax International Security Forum in Canada, he said "we're probably past the point" where a conventional airstrike would "take out" the program.
"Instead of a surgical strike on their nuclear infrastructure, I think we're to the point now that you have to really neuter the regime's ability to wage war against us and our allies. And that's a different military scenario," said Graham.
Iran is currently under four sets of U.N. sanctions, while the United States and European Union have imposed extra penalties for its refusal to stop enriching uranium.