Haaretz reports on a bill which would make it illegal for an Israeli to "launch or incite" a boycott against Israel:

Under the new law, any group could sue damages of up to NIS 30,000 from anyone who launched a boycott against them, or incited a boycott, without having to prove that damage was indeed caused. An additional sum could then be demanded once damages were proven.

The bill comes in response to a wide range of boycotts – financial, academic, and others – that have recently been encountered in Israel. Elkin said Tuesday that "we mustn't accept boycotts against Israel, whether academic or economic. The state must protect itself from the increasing processes of delegitimization, and provide compensation to those harmed by it."

"The wall-to-wall support of this bill proves that members of Knesset recognize the need to maintain a balance between democratic rights and the premeditated targeting of Israeli bodies," Elkin went on to say.

The article references a U.S. law "forbidding Americans from participating in boycotts on U.S. allies, including Israel." I don't think this is factually correct. My guess is that it's referring to the 1977 law making it illegal for U.S. citizens to participate in the Arab League boycott of Israel. This law is irrelevant to today's BDS movement as the BDS call is not related to the Arab League boycott, or called for by a foreign country. For more on this issue see this resource from the US Campaign to End the Israeli Occupation - Impact of Federal Anti-Boycott And Other Laws On BDS Campaigns (PDF).