A viral campaign has some fearing for the safety of Muslims in New York.

A letter sent to homes in the U.K. and circulating on social media in the United States says April 3, is "Punish a Muslim Day."

It encourages people to verbally and physically assault Muslims.

"The hopes of the person who wrote this was to create an atmosphere where you can harm someone because of their religious belief," Brooklyn Borough President Eric Adams said while holding a copy of the letter at a news conference. "This letter is despicable. This letter has the energy of someone who wants to do harm."

"Let's embrace the diversity that the city has to offer and send a strong message that it's unacceptable and won't be tolerated — any concept of attempting to harm a person because of their religious beliefs," Adams said.

Officials from the NYPD's Intelligence Bureau said there is no evidence of the threat gaining traction in the city, but because the letter went viral officials said they want to assure Muslim Americans living in the five boroughs that they are safe.

That effort includes increasing police patrols Tuesday at mosques and in neighborhoods with large Muslim populations.

Officials are urging Muslims to be vigilant, but not be scared to go out.

Police in the U.K. are still looking for whoever wrote the letter.