It used to be possible to send money to friends/family/anybody with Google wallet using a credit card for a fee of 2.9% + $0.30. Some people found it useful for meeting minimum spend requirements despite this high fee. Google has removed this feature and you can now only fund directly from your bank account or by using a debit card.
When reader, Gaurav asked about this, this is the response he received:
Thank you for asking about using credit cards in your Google Wallet. You can use your credit cards to tap-and-pay with your Wallet app, for online purchases with your Wallet, and to add funds to your Google Play Balance for shopping on the Google Play Store.
We used to enable credit cards to send money through Google Wallet and to top up Wallet Balance, but we discontinued that to protect all our customers (and Google) from suspicious activities often associated with credit cards. Also, banks frequently charge much higher fees for using credit cards than debit cards and bank accounts.To send money and to top up your Wallet Balance, please use your debit card or bank account.