可以使用AWS CDK Python库中的“aws_cdk.aws_wafv2.CfnWebACL”和“aws_cdk.aws_wafv2.CfnRule”的“Properties”属性来更改AWS WAF规则的操作。在这里，我们将假设您已经使用AWS CDK Python构建了需要更改规则操作的WebACL。

以下是代码示例，将规则操作更改为“ALLOW”：

from aws_cdk import (
    aws_wafv2 as waf,
    core
)

# 创建WebACL规则并将其添加到规则组中 
acl_rule = waf.CfnRule(self, "AllowRule",
                      name="AllowRule",
                      priority=1,
                      action=waf.CfnRule.ActionProperty(allow={}),
                      statement=waf.CfnRule.StatementProperty(
                         managed_rule_group_statement=None,
                         rule_group_reference_statement=None,
                         byte_match_statement=None,
                         sqli_match_statement=None,
                         xss_match_statement=None,
                         geo_match_statement=None,
                         ip_set_reference_statement=None,
                         regex_pattern_set_reference_statement=None,
                         rate_based_statement=None,
                         and_statement=None,
                         or_statement=None,
                         not_statement=None
                        )
                     )
                     
# 更改规则操作为"ALLOW"
acl_rule.action = waf.CfnRule.ActionProperty(allow={})

# 更新WebACL规则的属性
acl_rule.node.default_child.cfn_options.update({
  "metadata":{
    "cfn_nag":{
      "rules_to_suppress": [{
        "id": "W70",
        "reason": "This is an allowed rule"
      }]
    }
  }
})