"The verdict is very disappointing and we consider it unfair and we will contact immediately the legal defence team to study the possibilities of appealing it," Aljazeera general manager Waddah Khanfar said on Monday.
The channel said it was an unjust sentence and a dangerous and unprecedented action in the history of journalism.
"We still believe that our colleague Taysir is innocent of the charges against him," Khanfar added.
A Spanish court on Monday found Alluni guilty of collaboration with al-Qaida, sentencing the Syrian-born but naturalised Spaniard to seven years in jail.
Earlier, Aljazeera denounced the sentencing.
"This is a black day for the Spanish judiciary which has deviated from all the norms of international justice,"
Aljazeera news editor Ahmad al-Shaikh said.
"It is a verdict that is based on circumstantial evidence at best. This verdict is a big shock for us. We are convinced of Taysir's innocence," he added from Madrid, where he attended the sentencing.
"The verdict is very disappointing and we consider it unfair and we will contact immediately the legal defence team to study the possibilities of appealing it"
Aljazeera general manager
Al-Shaikh said Alluni's family would appeal against the
Qatar-based Aljazeera also said he should be released on bail for health reasons pending a hearing.
Alluni, who had insisted on his innocence throughout Europe's biggest al-Qaida trial, interviewed the group's leader Osama bin Laden in Afghanistan weeks after the 11 September 2001 attacks in the United States.
Spokesman for the Arab Human Rights Committee Haitham Manna told Aljazeera from Madrid that the Spanish chief judge had told human right observers that a sentence would be issued against Alluni
"However, I did not expect the chief judge would dare to sentence Alluni to more than two years in jail, simply because he was forced to issue a sentence against him," he said.
"He (the chief judge) was forced to fabricate a sentence to save the face of Spanish judicial and political police in this country," Manna said.
Alluni's wife Fatima al-Zahra (C)
with her five children
Manna added that he would meet the Spanish chief judge on Monday.
"I will tell him my opinion frankly. We will tell him we feel sorry he could not face the pressures imposed on him," Manna said.
The spokesman confirmed that heavy political pressures were imposed on the court to issue such a sentence.
"There is no single evidence that may lead to such a sentence," he said.
"When I asked the Spanish chief judge about bin Laden's interview, he told me he did not consider it an evidence against Taysir," he confirmed.
"Then, what is the new evidence? The chief judge said he would give me a CD of the evidence.
"I would delay our report to the international observers for a week in order to check the secret evidence the chief judge said he would give us," Manna added.
"I did not expect the chief judge would dare to sentence Alluni to more than two years in jail, simply because he was forced to issue a sentence against him"
Haitham Manna, spokesman, Arab Human Rights Committee
Accused of acting as a financial courier to the group while in Afghanistan, Alluni, who had faced a maximum nine-year term, said in testimony he was only doing his job as a journalist.
First arrested in September 2003, Alluni was later released on bail on health grounds - he suffers from a weak heart and back problems - only to be arrested again and jailed in Madrid in November 2004.
He was released to house arrest in March, but taken back into custody on 16 September.