Information Minister Ernesto Villegas said Chavez suffered internal bleeding but it was brought under control, CNN International reported.
"This process of recuperation ... will require a prudent time, as a result of the complexity of the surgical procedure, and also because of complications that came up in the surgery," Villegas said in a televised address.
Chavez underwent six hours of surgery Tuesday and his condition raised questions about whether he would be well enough to attend his inauguration Jan. 10.
"It would be irresponsible to hide the delicacy of the current moment and the coming days," Villegas said Wednesday in a posting on the ministry's website.
Chavez has designated Vice President Nicolas Maduro to succeed him if "something were to happen that would incapacitate me."