The Egyptian won gold with his first lift of 197kg but still struck a frustrated figure after failing to break the Paralympic record and his own world record.
'Thank God that I got the gold medal,' Othman said.
'I am disappointed, though, as I had promised the Egyptian people I was going to break a world record here.
'Unfortunately, I did not do it. I am sorry not to be able to do that.'
Silver in the men's -56kg category went to Nigeria's Anthony Ulonnam - his country's third medal of the day.
Ivory Nwokorie won the women's -44kg class as her first lift of 109kg proved enough for victory.
Nwokorie was joined on the podium by Cigdem Dede of Turkey after she managed 105kg, while Ukraine's Lidiia Soloviova took bronze with 100kg.
Nigeria also made it onto the podium in the -52kg category thanks to Ikechukwu Obichukwu.
China's Feng Qi won gold with a best of 176kg, while 19-year-old Obichukwu lifted a kilogramme less for silver.
Russia's Vladimir Krivulya also lifted 175kg with his final attempt but took bronze as he was heavier than his Nigerian counterpart.