The minister, however, did not speak about the nature of reaction and added that the government and Prime Minister Narendra Modi will take a call on it.
He stressed that the government "is very serious" about it.
"Something must have been wrong... Though I will not go into details of it because it is a very sensitive matter. When something goes wrong while you try to correct it you should also ensure that it does not happen again," Parrikar said at an event here.
"I will not go into the details of what we are going to do. But if required I can have a knee-jerk reaction also. Sometimes a knee-jerk reaction is also required," the minister said without elaborating.
"This country is a very responsible power, that does not mean I will sleep over this kind of terrorism that is being pushed across the border. How I do it, is entirely for the government and Prime Minister to decide," said Parrikar.
"We will take a proper reading of everything," he said.
Parrikar also quoted Prime Minister Narendra Modi as saying those behind the Uri terror attack will be punished and said: "We will look into how to punish. We are quite serious about it."
Eighteen soldiers died in the terror attack on an army camp in Uri, in Jammu and Kashmir, on Sunday. Four terrorists who attacked the camp were also killed.
The terrorists were said to be carrying food and medicine packets with Pakistani markings, and Director General of Military Operations Lt. Gen. Ranbir Singh has spoken to his Pakistani counterpart expressing concern over the incident.
Foreign Secretary Jaishankar summons Pakistan High Commissioner Basit: MEA.
Three days after the terror attack in Uri sector, Pakistan High Commissioner to India Abdul Basit was summoned by Foreign Secretary S Jaishankar on Wednesday.
"We demand that Pakistan lives up to its public commitment to refrain from supporting & sponsoring terrorism against India #UriAttack," MEA India said in a statement.