Anupam, who has shared screen space with De Niro in O Russell's Oscar-winning film, "Silver Linings Playbook" shared on micro-blogging website Twitter that he was "privileged" to be invited for the 72nd birthday of the "Raging Bull" star on Monday.
"Privileged to be invited by Mr. Robert De Niro for his birthday in NY. Met up with David O'Russel and Bradley Cooper," Anupam wrote.
The 60-year-old actor, who is currently touring the US for his play "Mera Woh Matlab Nahi Tha", also met film director George Lucas of "Star Wars" fame at De Niro's birthday party.
"Genuinely believe that #KucchBhiHoSaktaHai. Never thought will meet George Lucas in Robert De Niro's birthday party," he tweeted.