Republicans “don’t get to demand ransom in exchange for doing their jobs”, Mr Obama said, by demanding concessions in policy before reopening government.
The US government shut down last week when Congress failed to agree a budget.
Republican leaders on Tuesday renewed their calls for Mr Obama to open negotiations over ending the impasses.
Republican House Speaker John Boehner told reporters: “What the president said today was if there’s unconditional surrender by Republicans, he’ll sit down and talk to us. That’s not the way our government works.”