Read MoreWhy Hong Kong scares markets
That said, the Wharton School professor of finance said if the situation "snowballs" into one like Russia and Ukraine and sanctions are imposed, that could be a serious development.
"I don't think that is in the cards at all. I think that is a very low probability event but let's keep our eye on it. There's always going to be uncertainties in world politics," Siegel said.
Read MoreHong Kong protests explained
The pro-democracy protests continued early Tuesday morning in Hong Kong. The protesters have called on the city's leader Leung Chun-ying to step down after Beijing last month announced a plan to limit 2017 elections for Hong Kong's leader, known as the chief executive, to a handful of candidates loyal to Beijing.
China rules Hong Kong under a "one country, two systems" formula that accords the former British colony a degree of autonomy and freedoms not enjoyed in mainland China, with universal suffrage set as an eventual goal.
Read MoreEconomics plays large role in Hong Kong protests
In other market news, Siegel stuck with his prediction that the Dow Jones industrial average will hit 18,000 by year-end.
"If you don't see a recession in the cards, and I don't see a recession in the cards, this is still, I think, a very good market."
—Reuters contributed to this report.