Ashraf Jumma says police threatened to seize a screen and a VCR on Thursday and arrested some of the more than two dozen attendees. Police also detained journalists, watched footage from the event and made them promise not to air it.
Hamas officials could not be reached for comment.
Hamas has banned public commemoration of Arafat's death since it seized control of Gaza in 2007 from forces loyal to Arafat's successor, Palestinian President Mahmoud Abbas.
In the West Bank, Abbas addressed thousands of flag-waving supporters near Arafat's grave, calling for national unity.
Published 11 November 2010, 12:22 IST