Cal. Civ. Proc. Code § 2076

The person to whom a tender is made must, at the time, specify any objection he may have to the money, instrument, or property, or he must be deemed to have waived it; and if the objection be to the amount of money, the terms of the instrument, or the amount or kind of property, he must specify the amount, terms, or kind which he requires, or be precluded from objecting afterwards.