The Shiv Sena faction headed by Thackeray is a part of the opposition alliance in Maharashtra along with the Congress and the NCP.
While Pawar has asserted that he has no plans to join hands with the BJP, his ally is making no bones about its disapproval of the meetings.
Rajya Sabha MP and Shiv Sena (UBT) leader Sanjay Raut responded to Pawar's remark that there is nothing wrong with him meeting his nephew.
"Sharad Pawar is saying Ajit Pawar is his nephew and can meet him. Why are their followers fighting on the streets then?" Raut asked.
In what appeared to be a swipe at the veteran leader, he said, "We don't put up appearances by sitting with another party's leaders as our workers fight."
He described Pawar as the "Bhishma Pitamaha" of Maharashtra politics and said he "should not do anything that creates doubt in the minds of people".
Raut said they had spoken to Maharashtra Congress chief Nana Patole over Pawar's meeting with Ajit Pawar.