Cashin, director of floor operations at the NYSE for UBS, spoke after the United Kingdom on Friday raised its terror threat to "severe."
Read MoreUKraises terror threat level: 'Attack highly likely'
Wall Street also tracked the situation between Russia and Ukraine, with fighting between separatists and government forces reportedly intensifying and NATO releasing satellite images of Russian troop movements in eastern Ukraine, a claim dismissed by Russia.
Still, though stocks fluctuated only slightly in midmorning trading, indicating investors were largely shrugging off mounting geopolitical tensions.
"They're having a little sigh of relief in the sense that no new shoe has dropped, and the 'invasion' appears to be limited to something under 1,000 people," Cashin said.
Read MoreRussia-Ukraine: Wall Street bets on limited impact
Given the myriad conflicts around the world, Cashin recommended investors keep tabs on current events over the weekend.
"We really want to watch the news tickers and unfortunately, the rumor mill."
—By CNBC's Drew Sandholm. CNBC.com contributed to this report.