"Dastardly ambush by Pakistan last night at the Chakan da Bagh area of Poonch leading to death of five Indian soldiers is unacceptable," Modi said in a tweet.
"From China's intrusions to Pakistan's ambushes- UPA government has been absolutely lax in securing the Indian borders. When will Centre wake up?" Modi wrote on the micro-blogging site twitter.
"My heartfelt condolences to the families of the brave soldiers who laid down their lives in Poonch," he tweeted.
A Subedar and four jawans of the 21 Bihar Unit were killed in the attack which took place at around 2 AM.