The statesman said that the US should determine such a line without publically announcing it, and without allowing Tehran to cross it.
Kissinger also said that any decision made in regards to preventing Iran from pursuing nuclear weapons should be made by the US alone.
Washington, he noted, cannot "subcontract" such a decision to Israel.
"We cannot subcontract the right to go to war. That is an American decision," he stressed.
"Should we make a public announcement (on red lines) that can be used by Israel as a justification for its going to war?
That we cannot do."
The United States, he continued, "Should draw a private red line" that "can be "publicly decided in terms of tactical necessities."
The former secretary of state noted that while the world would rather see a diplomatic solution to the Iranian nuclear crisis, that too has its limits: "A point will be reached where (the West) will have to define what they mean by unacceptable."
Speaking of the nearing US presidential elections,
Kissinger voiced his support of the Republican candidate: "I'm endorsing Governor Romney…
he would conduct responsible foreign policy. I won't go beyond that."
Meanwhile, the Wall Street Journal reported Friday that the US and the EU are working on new coordinated measures meant to increase the financial pressure on
Iran, and accelerate the recent plunge of Iran's currency.
Measures are also explored on how to further drain Tehran's foreign currency reserves.
A number of additional banks are also expected to be targeted for sanctions, the report said.