Ok, I found a solution:
1. During configuring the SQL datasource, at "Configure Data Source Parameters" step, make sure you select correct DbType for the parameter, for value select New Report Parameter.
2. On ASP.NET page that host Report Viewer, add this code:
//Create a new instance of the Report1
Telerik.Reporting.Report report1 = newReport1();
//Set a value to a Report Parameter, not to SQL parameter