"Gauri was a trenchant critic of obscurantism and conservative values. The silencing of a journalist in this manner has dangerous portents for democracy.
"We demand that the government apprehend the perpetrators at the earliest and expose those behind this planned murder of a senior woman journalist," IWPC said in a statement.
IWPC will tomorrow hold a joint protest with the Press Club of India and the Press Association.
Gauri, aged 55, was shot dead by unidentified assailants at the entrance of her residence in Rajarajeshwari Nagar.