Colvin's relatives sued the President
and his government last week, accusing senior officials of hunting down the journalist and killing her in a rocket attack four years ago.
In the wrongful death complaint, relatives said the attack was premeditated and aimed at silencing journalists in a bid to crush the political opposition.
But the President said his government had nothing to do with the killing and did not even know the celebrated journalist.
"The army forces didn't know that Marie Colvin existed somewhere because before that we hadn't known about Marie Colvin."
'She came illegally to Syria'
Assad accused the journalist of entering Syria illegally, saying his government is only responsible for those who enter the country lawfully.
"It's a war and she came illegally to Syria, she worked with the terrorists and because she came illegally, she's responsible of everything that befell her," he told NBC News in the interview later posted on Syrian state media.
Colvin, 56, a Yale graduate who reported on the war's human toll, had worked in conflict zones for years.
In the lawsuit, relatives said the Syrian military tracked and intercepted broadcast signals of Colvin and other journalists to determine their location.
The journalists had set up a makeshift media center in a volatile neighborhood in Homs, where they reported on the suffering of civilians in the city besieged by the military.
Tips from intelligence sources
In February 2012, Syrian forces launched a campaign against the neighborhood with artillery and sniper fire, according to the court documents.
French journalist Remi Ochlik also died in the strike, while British photographer Paul Conroy, Syrian activist Wael al-Omar and French journalist Edith Bouvier were injured.
The documents alleged the Syrian government got tips from intelligence sources on foreign journalists traveling from Lebanon to Syria.
Throughout the civil war, the Syrian regime has denied targeting civilians -- though it has referred to members of the opposition as "terrorists."
Colvin's relatives alleged there were "no lawful military targets," such as armed rebels, in the vicinity of the media center.
The strike occurred before rebel groups such as Al Nusra and ISIS gained a strong presence in the city, according to the documents.
Symbol of fearlessness
The celebrated war correspondent for Britain's Sunday Times had already been wounded in a conflict zone, losing her left eye when she got hit with shrapnel during her coverage of the Sri Lankan conflict in 2001.
She wore a patch on that eye, which became a symbol of her fearlessness.
Hours before her death, she talked to CNN's Anderson Cooper, describing her anger and fear on the shelling of civilians in the city.
It's "a complete and utter lie that they're only going after terrorists," she said during the interview.
The Center for Justice & Accountability filed the suit on behalf of Colvin's sister and niece in Washington. It seeks compensatory and punitive damages.