San Francisco (CNN) Boulders put out by a group of San Francisco neighbors to deter homelessness and drug dealing have been removed by the city, Public Works Director Mohammed Nuru said Monday.

The neighbors raised more than $2,000 through Facebook for 24 boulders, which they put on the sidewalks after they said the city wouldn't help them.

Nuru said the boulders were removed because in the past few weeks people were pushing them into the street, which he said is very unsafe. His agency was responsible for pushing the rocks back onto the sidewalk, and he said it became a daily occurrence and wasted city time.

Nuru also said the neighbors were getting calls from homeless advocates and were receiving hate mail.

"We're at the drawing board now. We're definitely going to look at some of the things we have learned," Nuru said. "It could be bigger boulders, it could be some kind of landscaping, it could be something different, but we're going to work with the neighbors on something they want."

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