Hi @zlibra 

SharePoint has some boundaries and limits. You are encountering the List View Threshold. 
The default for SP2013 is 5,000.

You need to get your SharePoint Admin to increase the View Threshold Limit.

Your message states a 7,000 list view threshold - so your Admin probably knows how to set this limit 

Refer to these links

Software boundaries and limits for SharePoint 2013 

Software boundaries and limits for SharePoint Servers 2016 and 2019 

@zlibra your admin has already raised the limit by 2000 from the default limit provided by Microsoft.

I don't know your farm configuration and content size but if your admin change increase the threshold value then it's going to be applied to each and every lists you've in that farm, it cannot be configured for certain list.

Best thing you can do is if you have any columns whose value can be control by site owners e.g. choice columns, people or group picker then you can index such columns and create different views (by leveraging filters and grouping) so that items in each view will be below your threshold limit.