"We came to ask for his release," said Umm Saad, one of Zaidi's three sisters.
His brother Uday accused the government of pressuring Zaidi into writing a letter of apology to Prime Minister Nuri al-Maliki.
Umm Saad said of her brother that "nothing is known about... his condition, but he did nothing wrong. On the contrary, he pleased everyone. Bush is an occupier and he is the source of all the orphans and all the widows in Iraq.
AFPThirty relatives of the journalist staged a rally outside the "Green Zone"
©AFP Ahmad al-Rubaye
"Everybody would have done what Muntazer did. We gave him the last kiss of democracy," she said of her brother shouting at Bush: "It is the farewell kiss, you dog."
On Thursday, investigating judge Dhiya al-Kenani denied bail to Zaidi, saying it was for his own protection.
But he said the journalist appeared to be in good health and bore only signs of blows to his face. This contradicted claims by another brother that Muntazer had suffered a broken arm and ribs, as well as injury to a leg.
His Brother Uday said on Friday: "It is clear that the judge is bound to the government. It is normal to make such statements."
Of Muntazer's reported apology to Maliki on Thursday, he said: "This apology is not a real one. If they (the government) want an apology, they must first release him so he can do it freely and not under pressure."