soft-pedal

By analogy to use of the left-hand pedal on a piano which is used to dampen the strings, making notes duller or softer.

soft-pedal (third-person singular simple present soft-pedals, present participle (UK) soft-pedalling or (US) soft-pedaling, simple past and past participle (UK) soft-pedalled or (US) soft-pedaled)

1. To attempt to persuade without being obvious about it, by understating a position so the listener takes the good points as obvious.
2. To tone down, damp, mute or obscure something; to proceed in a less forceful, circumspect or subdued manner.

• soft sell