In an interview on state news channel TRT, he said OSCE members had attended 'No' campaigns before the referendum.
On Monday, the OSCE said a "lack of equal opportunities, one-sided media coverage and limitations on fundamental freedoms” had created an “unlevel playing field" for Turkey’s constitutional referendum.
"In general, the referendum did not live up to Council of Europe standards. The legal framework was inadequate for the holding of a genuinely democratic process," said Cezar Florin Preda, head of the delegation from the Parliamentary Assembly of the Council of Europe.
Cavusoglu said visiting OSCE delegation "did not come with good intentions this time and made political remarks, rather than technical [ones]."
"The draft report they prepared has a lot of false technical data, showing that they are biased," said Cavusoglu. "Being anti-Islam has become synonymous with being anti-Turkey."
On Sunday, a majority of Turkish voters cast ballots in favor of 18 constitutional amendments, primarily aimed at switching from a parliamentary to a presidential system of governance.