Pakistan had reportedly launched 'strikes' against militant bases in Afghanistan on Saturday.
The blast took place during Dhamaal -- a Sufi ritual -- when hundreds of devotees were present inside the premises of the vast mausoleum of the saint.
A powerful car bomb exploded outside a Shiite imambargah at a busy market.
Official said the crackdown would be intensified in the coming days as government had resolved to eliminate militancy.
Punjab Law Minister Rana Sanaullah said the blast seemed to be aimed at sabotaging the Pakistan Super League final in Lahore.
Operation Radd-ul-Fasaad launched to fight terrorism across country.
The Global Terrorism Index 2017 released by the Australia-based Institute for Economics and Peace provides a comprehensive summary of the key global trends and patterns in terrorism over the last 17 years in covering the period from the beginning of 2000 to the end of 2016. According to the report, this is the second consecutive year, deaths from terrorism declined. Over the two years there was a decrease of 22 per cent compared to the peak of terror activity in 2014. Terrorism deaths have fallen significantly in Syria, Pakistan, Afghanistan and Nigeria. However, Islamic State defied this positive trend with over 9,000 deaths, primarily in Iraq and increased activity in OECD countries.