The construction workers said that they were rather building a wall for a hospice.
"A heavy security presence was deployed to the town and remained overnight to make sure there are no more clashes," the official said.
Copts, who make up 10 per cent of Egypt's 80 million population, complain of frequent discrimination.
In January, armed men fired on worshippers leaving a Christmas Eve service in the southern town of Nagaa Hammadi, killing six Copts and one Muslim policeman.
Three people are being prosecuted over the attacks.