Shahzad Masih, who was 26, and his pregnant wife Shama Bibi, 24, were beaten and tortured by the mob, before they were burnt alive in the kiln at the factory where they worked.
The parents have left four other children.
Pakistani police have since arrested 43 people in connection with the "blasphemy" killings, but several reports say hundreds were in the mob which killed Shahzad Masih and Shama Bibi.
Police summoned to the scene were unable to stop the mob, because there were too many of them.
This petition was started by Wilson Chowdhry, from the British Pakistani Christian Association (BPCA).
It calls the government of Pakistan to "Ensure the impunity for hate attacks against minorities stops by guaranteeing that perpetrators are convicted. In previous similar incidents the attackers have been set free after a short period in remand.
"Abrogate the biased blasphemy laws of Pakistan that have been used as a tool for discrimination against minorities and to settle personal vendettas or to steal another's possessions.
"Shut down any mosque that ever incites hate attacks through preaching murder over a loudspeaker.
"Implement laws that immediately free bonded labourers and act upon the laws immediately, to end modern day slavery in Pakistan."
It also calls on the rest of the world to "...terminate subsidies [to the country of Pakistan], until the nation improves its extremely poor human rights record."
The BPCA is protesting outside Downing Street this Saturday, and has also set up a benevolence fund for the family of Shahzad Masih and Shama Bibi.
Prime Minister Nawaz Sharif has called their murders "an unacceptable crime".
In a statement, he said: "a responsible state cannot tolerate mob rule and public lynching with impunity.
"The Pakistani state has to act proactively to protect its minorities from violence and injustice."
