Six cops were injured in clashes between protesting Samajwadi Party workers and the police force at Commissioner Chowk in Meerut on Monday.
The SP workers were protesting against the Lakhimpur Kheri violence that left eight people dead and several injured on Sunday.
Police said three injured policemen had to be administered medical treatment in Meerut.
The protest in Meerut turned violent and SP workers splashed petrol on cops, including the senior superintendent of police.
Police said they were preparing to initiate action against the attackers and the process to identify the culprits through CCTV footage was on.
Opposition parties staged nationwide protests condemning the Lakhimpur Kheri incident.
The Congress said it will hold protests outside the offices of all district magistrates across India on Tuesday to protest the incident.
On Monday, too, Congress leaders protested outside UP Bhawan in Delhi and staged agitations in other cities and towns.
Congress general secretary Priyanka Gandhi Vadra is also on a hunger strike after being detained at a guest house in Sitapur.
Videos of her lashing out at police personnel for misbehaving with her and her colleagues are also doing the rounds.
Eight people were killed on Sunday as violence erupted during a farmers’ protest, claiming the lives of both farmers and BJP workers ahead of a visit to Lakhimpur by deputy chief minister Keshav Prasad Maurya.