The world has been “narrowed down” by the death of the Israeli literary giant Amos Oz, according to his close friend and fellow author David Grossman.

“There will not be another Amos Oz, there was only one like him. You can say this about every human being, of course, but there was something unique about Amos,” Grossman told the Observer.

“Those who appreciated him – and not only appreciated, but needed his clear, sharp voice – have lost someone who made their lives better. When a person like Amos – a man of such grandeur, and I don’t say that easily – passes away, the world is diminished a little, it’s narrowed down a little.”

Oz, who died on 28 December aged 79, was one of Israel’s best-known writers and intellectuals, and a prominent advocate for peace with the Palestinians. His books were translated into dozens of languages, and his acclaimed autobiography, A Tale of Love and Darkness, was made into a film in 2015, directed by Natalie Portman.

Speaking by telephone from San Diego, Grossman said: “He was an international figure, but for me first and foremost he was a friend, a dear and very close friend, and it’s so painful to think of a world without Amos.”

He praised the distinctive style and depth of Oz’s writing. “You read one paragraph, and you knew you were reading Amos Oz. He insisted on nuance, both in his literary work and his political activity.”

Oz and Grossman, along with AB Yehoshua, were regarded as the hallowed trio of Israeli literature and the collective liberal conscience of the nation. As well as being showered with literary prizes, each spoke out against Israel’s occupation of Palestinian land and for peace.

Grossman last saw his friend six weeks ago. “Whenever I came out of a talk of ours I felt that I had been enriched. Every month or so, I would come to his home and we’d have coffee and talk about everything that interested us.

“I consulted a lot with him about my writing, and sometimes he asked me about his writing. And because I told him exactly what I thought – when I loved something, when I didn’t like something – it fostered our friendship. Above all, he was a human being, he was a mensch, he was warm and generous and curious, and he wanted to know family details and what I was doing, and he shared with me things. [His death] is really such a painful thing.”

A Tale of Love and Darkness was Oz’s greatest work, said Grossman. “It’s not only his autobiography, but in a way the biography of Israel even before it was created.”

Facebook Twitter Pinterest David Grossman says it is painful to think of a world without his friend. Photograph: Simone Padovani/Awakening/Getty Images

The bestselling memoir – which was translated into Arabic – describes Oz’s childhood in Jerusalem, the suicide of his mother when he was 12 and his move to a kibbutz three years later. Oz addressed politics and the conflict with the Palestinians in his nonfiction writing and articles. “Three weeks after the Israeli victory in the six-day war in 1967, he wrote about the catastrophe of the occupation,” said Grossman.

“When all Israel was swept by the euphoria of the unbelievable military victory, he immediately recognised that this occupation is going to corrupt us, and how heavy the price we shall pay for this corruption, and how we shall fall in love with the occupation – exactly everything that has happened to us and has turned into our tragedy. Always he was himself, he was unbribable, unchangeable, very solid and yet very clear.”

In recent times, he did not expect to see peace in his lifetime. “He said it will take many years. The hatred is too deep, the suspicion is too deep, the power of fear is so strong, and there are always people who try to inflame hatred and suspicion.

“But knowing it will take many years did not make him shy away from endless efforts to keep this final option, to insist on imagining what peace will look like. Right now, peace looks very far away and unreachable, but he knew there will come a day – in a decade or five decades – when there will be peace. We don’t know what will bring it about, what will overcome hatred and animosity and violence, but there will be such a moment.

“Amos always said the drama of the conflict between Israel and the Palestinians will not end like a Hollywood movie, and we all walk into the sunset hand in hand, but it will be a realistic, down to earth peace, [given] the limitations of the parties involved that have been distorted by war for so many years.”

Oz knew his views were not popular, said Grossman. The Israeli political landscape has become significantly more rightwing, with the once prominent pro-peace faction virtually silenced and frequently vilified. “It was painful for him, but he understood it. He said it’s not very popular to advocate trusting your enemy, the natural thing is not to trust. But he believed we should trust the enemy, we have to become trustworthy in the eyes of the enemy and they have to become trustworthy in our eyes.

“He was a very strong advocate of the two-state solution. The fact that it’s less and less popular doesn’t mean it’s not the true and only possible solution.”