Several posters, which were first spotted near Broadway and Carlton Street on Friday night, attack the integrity of Katz — who is Jewish — and make references to Hitler.
The posters also allege that Katz and "members of Winnipeg's business community are involved in questionable business transactions," city police said in a release.
"I was rather saddened. I was extremely disgusted," Katz told CBC News late Sunday.
"I mean, any time I see acts of racism — in this case, anti-Semitism — it certainly is disturbing to me."
The Winnipeg Police Service noted that the posters were not signed. They did not say how many posters have been found.
The police force's major crimes unit is investigating. Anyone with information about who may have put up the posters is asked to contact police.
Katz said whoever is responsible for the posters should come forward.
"I only hope that those who are, you know, responsible for fanning the flames of racism and anti-Semitism have the courage to basically stand up and admit to it," he said.
Posters appear before Rosh Hashanah
News of the anti-Semitic posters come as members of the city's Jewish community mark Rosh Hashanah, the start of the Jewish New Year, on Sunday.
B'nai Brith Canada condemned the posters and urged those who know who is responsible to come forward.
"Bringing anti-Semitism into the debate about city hall is simply wrong. Implicating a large group of individuals with the brush of racism is most disturbing," Frank Dimant, B'nai Brith's chief executive officer, said in a release Sunday.
Salisbury House president Earl Barish, one of the businesspeople named on the posters, called the messages "despicable."
"It is unfortunate that there are still people who have such hate within that they would print and post these despicable posters," he said in a statement Sunday.
"There is no room for these posters in a peaceful society," he added. "I have spent most of my life trying to do positive things in Winnipeg and to make this city a place where we can all live together in harmony."
'It never seems to stop'
David Matas, a B'nai Brith representative from Winnipeg, said the posters constitute a hate crime.
"It's testimonial to the permanence of anti-Semitism. It seems never to stop," Matas told CBC News.
"It's the oldest and the strongest hatred, and it's kind of discouraging to see it here."
Federal Public Safety Minister Vic Toews, who is the member of Parliament for Manitoba's Provencher riding, said he was "shocked and disgusted" to hear about the posters.
In a release issued late Saturday, Toews said Canadians have "no tolerance for anti-Semitism of any kind and today I continue to stand with the Jewish community in Winnipeg."