Published Monday, 28 July 2014
The party's main constituency offices at Ráth Mór on the Eastway Road was targeted late on Sunday.
Police said a rear window was broken and a flammable liquid poured through shortly before midnight.
The scene was held overnight and police investigations are continuing.
A fire service spokesman said crews dealt with the blaze for around an hour.
He added: "It was a relatively small fire which we managed to contain quickly.
"Damage was caused to offices in one section of the building and we are treating the incident as deliberate."
Sinn Féin said it was "business as usual" at the offices on Monday.
MLA Raymond McCartney said: "This must be condemned as an attempt to attack the democratic process.
"It will not stop us working or the people of Derry.
"It will be business as usual for Derry Sinn Féin, continuing to serve the people of the city and the wider north west."
Police are appealing for information.
© UTV News