A surveillance video from a nearby store showed a man writing on walls and windows along Point Breeze Avenue, including the United Muslim Islamic Center.
The center's president, Qasim Rashid, said the vandalism was clearly targeting their faith. He also said he saw similar messages on another building across the street.
He said these incidents have increased since the start of the war between Hamas and the Israeli regime.
The Council on American-Islamic Relations of Philadelphia (CAIR-Philadelphia) has urged police to investigate it as a hate crime.
"All mosques, all synagogues, churches, and houses of worship should be safe from any threats. should be safe to worship as they do and this value should be non-negotiable for anyone even in times of tension or conflict," said Ahmet Tekelioglu, executive director of CAIR-Philadelphia, CBS News reported.
The Muslim community said they were not intimidated by the vandalism and would continue to worship at the mosque.
The police said they were still investigating the incident and did not confirm if they were treating it as a hate crime.
There has been a rise in anti-Muslim hate crimes in various countries in North America and Europe following the start of the war in Gaza.
Source: Agencies