Violence against Muslims in India was also reported after Sunday's emphatic 10-field victory, Pakistan's first against India at any World Cup.
Cricket clashes between India and Pakistan frequently increase tensions between the neighbors, which have fought three wars since their independence in 1947.
Shami, 31, became the main target after the defeat in Dubai, despite the fact that the captain of India virat Kohli he acknowledged that his team had been "outmatched."
Hundreds of messages were left on Shami's Instagram account saying that he was a "traitor" and that he should be expelled from the Indian team.
But many fans and politicians also asked for support for him, asking Indian players to reject hateful messages as they had endorsed the Black Lives Matter movement by kneeling.
"Team India, your BLM knee counts for nothing if you can't stand up for your teammate who is being horribly abused and controlled on social media." Omar Abdullah |, former Prime Minister of cashmerehe said on Twitter.
#MohammedShami was one of 11 players who lost last night, he was not the only player on the field. Team India your Bโฆ https://t.co/El2CGszwG4
- Omar Abdullah (@OmarAbdullah) 1635141492000
"Ignore the haters, the majority of India is grateful for your effort," said another supporter on Instagram.
People started celebratory shots in the Pakistani cities of Islamabad and Karachi after the famous victory, while firecrackers were reportedly lit in Kashmir.
The online attack on Mohammad Shami is shocking and we support it. He is a champion and anyone who uses Indiโฆ https://t.co/sFDXLPF708
- Virender Sehwag (@virendersehwag) 1635153241000
Gautam Gambhir, a former cricketer from India Test who has become an MP for the Bharatiya Janata Party, said it was "shameful" that people were celebrating Pakistan's victory.
Those cookies that explode in Pak's victory can't be Indian! We support our boys! #Shameful
- Gautam Gambhir (@GautamGambhir) 1635145681000
In Punjab, Kashmiri students said they were beaten.
A student at an engineering and technology institute said dozens of men armed with hockey sticks and clubs attacked them as they watched the final stages of the game.
I was even part of the #IndvsPak battles on the field where we lost but we were never told to go to Pakistan! I'm talkingโฆ https://t.co/gYiENL171p
- Irfan Pathan (@IrfanPathan) 1635156694000
"They entered our room, turned off the lights and beat us. They destroyed our laptops," the student told AFP, who requested anonymity for fear of further problems.
We love you @ MdShami11 ๐ฎ๐ณ #Shami
- Harbhajan Turban (@harbhajan_singh) 1635160396000
"We are safe now and we have the support of our university. But we did not expect this at all. We are Indians."
We are so proud of you @ MdShami11 bhaiya ๐ฎ๐ณ
- Yuzvendra Chahal (@yuzi_chahal) 1635160511000
The party also sparked violence in neighboring Bangladesh. Two Pakistani supporters were beaten up by Indian fans while celebrating victory in a southern district, media reports said.