"The situation has barely changed so far since the previous (UPA) regime. The meeting between the two (Modi-Sharif) is an unfortunate development," said Thackeray, whose party Shiv Sena is a part of the BJP-led NDA.
He said Pakistan was "everyday killing our soldiers" and the people of India have great expectations from Modi that he would give them a fitting reply.
"Recently, the Indian Army went inside Myanmar to eliminate terrorists there. I don't know if they have learnt any lessons from that but Pakistan needs to be taught a lesson as well," Thackeray told mediapersons.
Referring to the meeting in Ufa and the proposed visit by Modi to Pakistan next year, the Sena chief lamented that whatever was happening earlier was continuing.
"People are saying nothing has changed... The same traditions that were followed earlier are still being followed. People have a lot of expectations from Modi to give a fitting reply to Pakistan... Don't belie those expectations," he said.
On Friday, Modi and Sharif held talks on the sidelines of the Shanghai Cooperation Organisation (SCO) summit in Russia.
During the 45-minute meeting, Modi accepted Sharif's invitation to visit Pakistan for the Saarc summit in 2016, which has ruffled the Sena's feathers.