Aljazeera's Baghdad bureau chief, Abd al-Haq Saddah said the channel's staff was barred for one month, from 28 January to 27 February.
"By continuing to penalise media in Iraq, the IGC discredits its professed support of a free press," CPJ Executive Director Ann Cooper said.
The IGC had prevented the channel's staff from attending a press conference on 29 January, held by then IGC president Adnan Pachachi in Baghdad.
The channel was then subsequently informed, via fax to its Qatar headquarters, that its reporters were barred as a result of the IGC's unhappiness with a programme aired on Aljazeera which the council felt had criticised the interim government.
Pachachi reportedly said Aljazeera had broadcast a "provocative programme in which one of its participants was very excessive (in their remarks) and made accusations against certain council members."
The controversial talk show, Opposite Direction, aired on 27 January featured an Iraqi Communist Party spokesman and an IGC spokesman discussing the topic of Israeli infiltration in Iraq.
Sharon is alleged to have visited
Iraq in secret
The communist party spokesman, Dr Nur al-Muradi, alleged, among others, that some IGC members have had relations with Israel or had visited the country.
He also alleged that Israeli Prime Minister Ariel Sharon had secretly visited Baghdad in December 2003, to attend a hearing of captured dictator Saddam Hussein.
"The IGC should welcome an open debate about Iraq's future, even if it includes views that the IGC finds objectionable or distasteful," said the CPG's Cooper.
It is unclear how strictly the ban will be enforced.
On 23 September, the Governing Council banned both Aljazeera and the Dubai-based al-Arabiya from covering government activities for two weeks for allegedly inciting anti-US violence.
Al-Arabiya was also given a two-month ban that was lifted only last month, for airing an audio-taped message from Saddam calling for attacks on the IGC.
Launched in 1996, Aljazeera has attracted international attention through its coverage of the US military campaign in Afghanistan and broadcasting videotaped statements of al-Qaida leader Usama bin Ladin.
Aljazeera also broadcast audiotapes by Saddam Hussein before his capture in December by US forces.