I do not think it means what you think it means

The Hill reports:

Republicans said tense negotiations over raising the $14.3 trillion debt limit at the White House ended when President Obama stormed out of the meeting with a stern warning to House Majority Leader Eric Cantor (R-Va.): “Don’t call my bluff.”

“It ended with the president abruptly walking out of the meeting,” Cantor told reporters upon returning to the Capitol Wednesday.

Our handy Merriam-Webster dictionary defines the transitive verb "to bluff" to mean:

a : to deter or frighten by pretense or a mere show of strength;
b : deceive;
c : feign [the catcher bluffed a throw to first].

By which I take the President to have meant that his position in these critical debt limit negotiations is a pretense, intended to deceive?

For purposes of argument, let's assume he meant not that he's bluffing, but the opposite. He meant to say, "Don't think that I'm bluffing."

In which case, what does that mean? That unless all agree to do what he's proposed . . . what? He will do what?