The head of the International Monetary Fund says that Greece's rescue creditors "will continue to work" for a deal to save the country even though Athens called for a referendum and advised Greeks to reject the proposals of international creditors.Parliamentarians late Saturday voted in favor of the referendum, a shock announcement by radical leader Alexis Tsipras after his government rejected the latest debt deal, saying it involved further austerity measures that would cause "humiliation" to the Greek people.The referendum on July 5 will ask Greeks to vote for or against the measures submitted by creditors to Athens on Friday at one of the final rounds of the negotiations. In a speech before parliament's vote, Tsipras said he was confident "the Greek people will say an emphatic 'no' to the ultimatum" by the country's European Union-International Monetary Fund (IMF) creditors, but "a big 'yes' to European solidarity."On the other hand, Christine Lagarde says that the creditors "always showed flexibility to adjust to the new political and economic situation in Greece," thus rejecting claims from Greek Prime Minister Alexis Tsipras that his country was facing an ultimatum. But Lagarde insists Greece needs to do more. "It requires a balanced approach, on the one hand there has to be structural reforms, deep ones, to change the Greek economy, to make it more productive, more efficient so that it generates growth and jobs." Once that's done, "it requires financial support" from the international partners, added Lagarde.