Mexico on Monday responded by recalling its own diplomat from Caracas. In an interview with CNN en Espanol, Fox said he would meet with Foreign Secretary Luis Ernesto Derbez to decide what to do next.
Tensions between Fox and Chavez spilled over after this month's Summit of the Americas in Argentina, where Fox defended a US-backed proposal for a Free Trade Area of the Americas while Chavez proclaimed the idea dead.
Mexico had said earlier on Monday it would expel Venezuelan ambassador Vladimir Villegas and recall its own ambassador to that country at midnight on Monday unless Chavez's government said it was sorry after the Venezuelan leader said on Sunday to Fox: "Don't mess with me, sir, because you'll get stung."
But in a news conference on Monday in the Venezuelan capital, Venezuelan Foreign Secretary Ali Rodriguez said his country would not accept Mexico's demands.
"The immediate return of ambassador Vladimir Villegas has been ordered," Rodriguez said, adding that his departure was "leaving the affairs of our embassy in Mexico in the hands of an appointed charge-d'affaires".
The Mexican president supports a
US proposal for a free trade area
Venezuela "rejects as an unjustified attack the ultimatum issued by the government of Mexico," Rodriguez said. "This situation is entirely the responsibility of President Fox."
Fox responded by saying he was going to continue to fight for free trade - the topic that sparked the dispute between the two leaders.
He promised to keep the debate with Chavez from becoming personal, but added "we can't allow people to offend our country".
In a statement late on Sunday, Mexico's Foreign Relations Department said that because Chavez's comments "strike at the dignity of the Mexican people and government, Mexico demands a formal apology from Venezuela's government".
Earlier, Fox spokesman Ruben Aguilar said withdrawing ambassadors wouldn't mean severing ties completely with Venezuela because business and cultural relations would remain intact.