The ADL, which opposes the BDS movement, and in fact usually is quick to pounce on any criticism of Israel, opposes the anti-boycott law.
from Haaretz:
The Anti-Defamation League (ADL) expressed serious concern over the recently passed boycott law on Tuesday, calling it an unnecessary impingement of Israelis’ basic democratic right to freedom of speech.
The league’s President, Abraham H. Foxman, who is currently in Israel, issued a statement Tuesday saying that while the ADL “has a long history of vigorous opposition to any and all boycotts of Israel”, the recently passed law runs counter to the league’s belief in the importance of democratic ideals.
...
According to the recently passed law, a person or an organization calling for the boycott of Israel, including the settlements, can be sued by the boycott's targets without having to prove that they sustained damage.
The court will then decide how much compensation is to be paid. The second part of the law says a person or a company that declare a boycott of Israel or the settlements will not be able to bid in government tenders.
http://www.haaretz.com/jewish-world/adl-boycott-law-impinges-upon-israelis-democratic-rights-1.372886