The former Rossoneri full-back believes that the 22-year-old is still held in the highest esteem by the club and is paying little heed to persistent rumours linking him with PSG
Pato has been plagued by persistent thigh problems this season and the Rossoneri tried to offload the Brazil international to Paris Saint-Germain during the January transfer window only for the player to reject the opportunity to join the Ligue 1 outfit.
It has been claimed that the deal could be resurrected at the end of the season but Serginho insists that his compatriot remains a valued member of Massimiliano Allegri's squad.
"With absolute certainty, Milan do not have the slightest intention of negotiating for Pato," the former Rossoneri full-back told Globoesporte.
"He is a very important player. Big clubs want him but I believe it is almost impossible he will leave."
Robinho has also been linked with a move away from Milan in recent weeks, with Santos keen to bring the player back to Brazil. However, Serginho cannot see this proposed transfer materialising either.
"Robinho is a major player," he argued. "If you analyse Milan's games this year, he was present in maybe 70 or 80 per cent of them.
"He is a player of great importance to the club and is part of their plans."
Serginho spent nine years at San Siro after joining Milan from Sao Paulo in 1999.