Restrict Permission to add New Team in Microsoft Teams

Restricting to add new team feature is not available out of the box in Microsoft Team Admin Center. But there is an alternate approach that you create a security group and then give permission to create team to this group only. Let's assume that you have created the group name 'Security Group Creation Allowed'

$GroupName = "Security Group Creation Allowed"
$AllowGroupCreation = "True"

Connect-AzureAD

$settingsObjectID = (Get-AzureADDirectorySetting | Where-object -Property Displayname -Value "Group.Unified" -EQ).id
if(!$settingsObjectID)
{
      $template = Get-AzureADDirectorySettingTemplate | Where-object {$_.displayname -eq "group.unified"}
    $settingsCopy = $template.CreateDirectorySetting()
    New-AzureADDirectorySetting -DirectorySetting $settingsCopy
    $settingsObjectID = (Get-AzureADDirectorySetting | Where-object -Property Displayname -Value "Group.Unified" -EQ).id
}

$settingsCopy = Get-AzureADDirectorySetting -Id $settingsObjectID
$settingsCopy["EnableGroupCreation"] = $AllowGroupCreation

if($GroupName)
{
    $settingsCopy["GroupCreationAllowedGroupId"] = (Get-AzureADGroup -Filter "DisplayName eq '$GroupName'").objectId
}
 else {
$settingsCopy["GroupCreationAllowedGroupId"] = $GroupName
}
Set-AzureADDirectorySetting -Id $settingsObjectID -DirectorySetting $settingsCopy

(Get-AzureADDirectorySetting -Id $settingsObjectID).Values