Yishai Montgomery, 26, has been dubbed the "guitar hero" by Israeli media and on social networks for his attempt to stop the attack, which killed an American tourist and wounded 12 people, before a policeman shot the assailant dead.
Stunned by his overnight fame, he has been swamped with media interview requests and has received several replacement guitars, including one from Israeli star Aviv Geffen.
Well-wishers have set up a $5,000 crowdfunding campaign for him.
Montgomery was playing on the beachside promenade in Jaffa, a picturesque Tel Aviv neighbourhood popular with tourists, when he saw a knife-wielding man attacking passers-by.
"For I moment I didn't understand that what I was seeing was real," he told AFP on Thursday.
He was quickly jerked to reality when the man, 21-year-old Bashar Masalha, ran toward him.
Signup to our newsletter and follow us on Facebook and Twitter!
Montgomery lashed out with his guitar, briefly stunning Masalha, then followed him as he ran off, shouting "terrorist" to warn others, until police shot him dead.
Since then, "I go from one interview to another," he said. "My phone doesn't stop ringing."
There are moments, Montgomery said, when he misses the calm of his home village in southern Israel.
But those thoughts are soon swept aside by the recording offers he has received and the promise of a boost to his musical career, which has been stalled since he returned to Israel in January from a three-year stay in Canada.
"I have no definite plans. I am open to any changes and to all proposals," he said.
But Montgomery has no illusions about the fleeting nature of fame.
"Tomorrow, everyone will have forgotten me," he said.
"But I don't care. I love guitars, and people have already given me four new ones."