The British and Dutch governments voiced disappointment with the result of Saturday's referendum, in which almost 60 percent of voters opposed the repayment deal.
"We must do all we can to prevent political and economic chaos as a result of this outcome," Prime Minister Johanna Sigurdardottir told state television.
The issue will now be settled by the court of the EFTA Surveillance Authority (ESA), the European trade body overseeing Iceland's cooperation with the European Union.
"My estimate is that the process will take a year, a year and a half at least, Finance Minister Steingrimur Sigfusson told a news conference.
