"I would say Asif was a victim of innocence. When he injured his elbow he took an injection for that, otherwise he was taking a powder which I was not aware of. When I came to know about it I stopped him," Lifson told AFP on Wednesday.
Asif told a doping tribunal last month that while in England with the Pakistan team in June 2006 he was given an injection for his elbow injury which did not work.
He received two more injections during his stay. After his return he had been using a nutritional supplement called Promax-50, he told the tribunal.
The 23-year-old Asif was banned for one year and fellow paceman Shoaib Akhtar for two years after internally-conducted tests revealed both had excessive limits of banned steroid nandrolone in their urine samples.
The tribunal in its verdict last week justified the lesser ban on Asif as he had little knowledge of doping and was never tested before, unlike Akhtar who was tested twice previously.
Akhtar and Asif were pulled out of Pakistan's Champions Trophy squad in India last month. They accepted the results of the tests before a three-member tribunal, which imposed the bans in line with the regulations of the World Anti-Doping Agency (WADA).
Lifson described Asif as serious and honest player.
"Asif takes training very seriously and is a fantastic guy to work with, honest, hard-working and a very good man," Lifson said.
Lifson, 26, who specialised at the University of Cape Town, South Africa, said news of pacemen testing positive was a shock.
"I was shocked and my first opinion was that there must be something wrong with the testing program. It was my opinion that there was something going on that Asif wasn't aware of, that he was given some supplement that I was not aware and may have given possible positive test."
Lifson said the Pakistan team management was taking effective measures to increase awareness of doping.