Egypt's president-elect Mohammed Mursi plans to take legal action against the Iranian Fars news agency for fabricating an interview with him.
Fars quoted Mursi saying the two countries should improve ties.
Such a move would go against Western efforts to isolate Tehran over its controversial nuclear program.
The official news agency Mena quoted Mursi's spokesman, Yasir Ali, as saying the interview was a fabrication.
Ties between Cairo and Tehran have been frosty since Iran's 1979 Islamic Revolution and the Egyptian-Israeli peace deal of the same year.
The two countries do not have full diplomatic relations, but each has a mission in the other's capital.
Fars claimed Mursi had "underlined his enthusiasm for the further expansion of ties with Iran, and said relations between Tehran and Cairo will create a strategic balance in the region".
On Monday, Iranian President Mahmoud Ahmadinejad congratulated Mursi for winning the election, state TV reported.
"I emphasize expanding bilateral ties and strengthening the friendship between the two nations," Ahmadinejad said.