You can try this code
transferTokensTo: function(contract, address_from, address, tokens) {
    return new Promise(function(resolve, reject) {
        contract.methods.decimals().call().then(function (result) {
            var decimals = result;
            console.log("Token decimals: " + decimals);
            var amount = tokens * Math.pow(10, decimals);
            console.log('Transfer to:', address);
            console.log('Tokens: ' + tokens + " (" + amount + ")");
            contract.methods.transfer(address, amount).send({
                from: address_from,
                gas: 150000
            }).on('transactionHash', function (hash) {
                console.log('\n[TRANSACTION_HASH]\n\n' + hash);
            }).on('confirmation', function (confirmationNumber, receipt) {
                console.log('\n[CONFIRMATION] ', confirmationNumber);
                resolve(receipt);
            }).on('receipt', function (receipt) {
                console.log('\n[RECEIPT]\n\n', receipt);
                // TODO: process receipt if needed
            }).on('error', function (error) {
                console.log('\n[ERROR]\n\n' + error);
                reject(error);
            }).then(function (done) {
                console.log('\n[DONE]\n\n', done);
            });
        });
    });
}