Green’s Dictionary of Slang

(US) a political or industrial tactic whereby a negotiator or leader attempts to talk two warring sides out of making unreasonable demands.

1969		Time 10 Oct. 57: As for jawboning, Nixon’s Republican advisors consider it unfair and almost immoral to single out individual companies or industries.
1976		P. Conroy Great Santini (1977) 317: ‘Are they fighting again?’ Bull asked his wife. ‘Let me mop the floor with them. Then there won’t be no more jawboning.’.