"We will just have to hope that he respects that wish tomorrow. Either he will or he won't. There's nothing that we can order him to do," said the lawyer, Geir Lippestad.
Lawyers for the victims of the massacre made the request, he said.
Breivik, who boasts of being an ultra-nationalist who killed his victims to fight multi-culturalism in Norway, was in good spirits on the third day of his trial Wednesday, Lippestad said.
"I would say he's always in a good mood," Lippestad told reporters after the day's legal proceedings.
Breivik was questioned in court about having met other ultra-nationalists in Liberia and London up to nine years before his rampage, and was somewhat evasive, reporters who attended the trial said.
Prosecutor Inga Bejer Engh said there was evidence to prove he had visited both places.
Breivik boasted Tuesday that he had carried out "the most sophisticated and spectacular political attack in Europe since World War II" when he carried out his gun-and-bomb rampage.
And he would do it again if he had the chance, "because offenses against my people and my fellow partisans are in many ways as bad," Breivik told the court on the second day of his trial. He planned his killings as a suicide attack, he said.
"I didn't expect to survive that day," he said.
Breivik faces trial on charges of voluntary homicide and committing acts of terror in the July 22 attacks. Eight people died in a bombing in central Oslo, then 69 people were systematically gunned down at a youth camp on nearby Utoya Island.
Breivik testified Tuesday and Wednesday after declaring Monday that he had carried out the massacre but was not guilty because the killings had been necessary. He was allowed to read a prepared statement in court Tuesday, taking considerably longer than the 30 minutes he was allotted.
He rejected what he said would be prosecution efforts to portray him as a "pathetic and mean loser" and an "antisocial psychopath." He said he represented a "European resistance movement" and "Europeans who don't want our ethnic rights to be taken away."
Lippestad said Breivik's statement was "hard to hear, and it is difficult to understand." But he said it was important to the trial, since his client wants people to see him as sane.
"It is probably because of his ideology and his thoughts about why he has done what he has done," Lippestad said. "He thinks that it won't have any effect if he is considered insane."
Breivik's trial is expected to last up to 10 weeks. A court translator initially said Breivik was claiming self-defense as the justification, but court officials corrected that Tuesday, saying the correct legal term was "necessity."
Experts have given different opinions about Breivik's sanity, which will be a factor in determining what punishment he receives if convicted. Sentencing options could include imprisonment or confining him to a mental facility. Norway does not have the death penalty.
Under examination by prosecutors, he claimed to be linked to two other individuals in Norway who are associated with the so-called Knights Templar ultranationalist movement. He said "militant nationalists" had drawn tactical inspiration from Osama bin Laden's terror network.
"We've taken a bit from al Qaeda and militant Islamists, including the glorification of martyrdom" and organization into one-man cells, Breivik said. He denied that what he called the "militant nationalist" movement was evil.
"We don't act to be evil. We're trying to save our nations, our ethnic group and our culture," he said.
His testimony is not being broadcast due to a court ruling.
Most of the relatives of the victims did not want Breivik's remarks televised, and presiding Judge Wenche Elizabeth Arntzen rejected Breivik's claim that airing it was a human right.
Court papers indicated the five judges hearing the case did not want the trial to become a platform for Breivik to air his political views, or for them to distract from the legal issues involved.
Breivik says his rampage was meant to save Norway from being taken over by multicultural forces and to prevent ethnic cleansing of Norwegians. In a 1,500-page manifesto attributed to him, Breivik railed against Muslim immigration and European liberalism -- including the ruling Labour Party, which he said was allowing the "Islamification of Europe."