Mr Eisa died in hospital an hour later from a fatal wound to his heart.
Pullen now claims he was defending the 17-year-old from attack because the victim was armed with a yellow craft knife.
CCTV cameras captured most of the fight at around 4.30pm on May 18 earlier this year.
John McGuinness, prosecuting, told jurors the two suspects did not know Mr Eisa and only "clapped eyes on him" for the first time just 15 minutes before the killing.
Pullen, the 17 year-old and two other friends aged 14 and 15 had met up outside McDonalds before heading into the shopping centre and taking the escalator to the first floor.
CCTV footage shows them walking past Mr Eisa, nicknamed Waseem, and his girlfriend sitting on a window ledge.
Mr McGuinness said: "Something is said or a look is given because Mr Eisa appears to be annoyed about something.
He gets up and appears to want to go after them but Salma Begum grabs his hand and holds him back.
"Her recollection is that as the group walked past, the [17 year-old] stared at Waseem.
"When Waseem stood up she took his hand and tried to restrain him, she didn't want him getting angry and aggressive."
After a further confrontation in a games arcade, the group followed Mr Eisa out into the car park area where the fight started.
Mr McGuinness said: "It was two onto one and though Eisa may have had a knife he did not get the opportunity to use it.
"Pullen stabbed Eisa no fewer than four times and did so with some force.
"In addition to the fatal wound to the heart, Pullen stabbed Eisa twice in the face and once in the his skull.
"When he inflicted these stab wounds he intended - at the very least - to cause Eisa really serious harm."
Pullen, of Romford, and the 17-year-old, also from Romford, both deny murder.
The trial continues.