The man was seen in footage and photos from a Jan. 5 news conference attended by Stenhouse and Fung.
"I've been in a meeting all night being a great public servant for the city of Warwick," Stenhouse told WJAR-TV Wednesday. "Now, I get this [expletive]. And you guys did not reach out to me. And that was a big lie on the news."
WJAR-TV said it reached out to Stenhouse, but she declined to comment prior to the airing of the original report on the man's appearance at the conference.
Stenhouse allegedly had the man dress as an elderly woman to make it appear she had the support of local seniors.
Stenhouse, a former Republican member of the Warwick, R.I., City Council, remains a member of the Warwick Planning Board. She unsuccessfully ran as a Republican for Rhode Island secretary of state in 2006.
Fung's office declined to comment further than confirming Stenhouse's resignation.
"The mayor doesn't comment on personnel issues," Robert J. Coupe, Fung's director of administration, told the Providence Journal.