Russia's massing of troops near its border with Ukraine has sparked Western concerns that it may invade. If Russia does make an incursion, the West has threatened sanctions with profound economic effects. Moscow has said it has no plans to invade.
"When it comes to sanctions, the purpose of those sanctions is to deter Russian aggression. And so if they are triggered now, you lose the deterrent effect," Blinken told CNN in an interview.
Blinken said if one more Russian force entered Ukraine in an aggressive manner, that would trigger a significant response.
The United Kingdom has threatened Russia with sanctions after Britain accused the Kremlin of seeking to install a pro-Russian leader in Ukraine.
Ukrainian President Volodymyr Zelenskiy told the Washington Post last week he supported imposing sanctions now, a view endorsed by Republican lawmakers on Sunday.
"We need to act now. When it comes to pushing back against Russia, we need to show strength and not be in a position of ... appeasement," Republican Senator Joni Ernst, a member of the Senate Armed Services Committee, told ABC News.
Democratic Senator Chris Coons, an ally of U.S. President Joe Biden, argued for passing bipartisan U.S. legislation to "show resolve and determination and apply some sanctions now" but said it was best to keep the strongest sanctions in reserve.
"The very strongest sanctions, the sorts of sanctions that we use to bring Iran to the table, is something that we should hold out as a deterrent," he told ABC News.
Asked if U.S. hands were tied over Ukraine because of a need for Russian support in talks on reining in Iran's nuclear program, Blinken, told CBS News: "Not in the least."
(Additional reporting by Susan Heavey; Writing by Arshad Mohammed; Editing by Scott Malone and Lisa Shumaker)
By Arshad Mohammed